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AEA Hydro Power Operations Maintenance Course 2008
ALASKA ENERGY AUTHORITY Hydro Power operations and Maintenance course seward, Alaska oct. 20 to oct. 31. 2008 course outline 1. october 20 Monday Introduction to Hydropower Production A. Hydropower Projects 1. Power production 2. Domestic water supply 3. Recreation 4. Irrigation 5. Flood control B. History of Hydropower Projects 1. Production 2. size 3. Alaska Hydro activities c. Housekeeping -lunch, breaks, quizzes, etc Electrical Theory D. Basic Electricity 2. october 21 Tuesday Electrical Theory A. Basic Electricity B. AC Fundamentals 3. october 22 wednesday A. First Aid B. CPR 4. october 2 3 Thursday safety A. Tool Box Meetings B. Job Hazard Analysis c. Equipment D. contacts E. Training F. Lock out safety Plan 1 (./ 5. Project Eguipment Components G. Generators 1. single phase 2. three phase a. Inouction b. Synchronous 3. i>C H. Transformers I. circuit Breakers J. Load Break Disconnect SWitches K. Drawings 1. schematics 2. wiring Diagram L. Turbines 1. Impulse a. Pelton b. Turgo c. Discharge chamber 2. Reaction a. Francis b. Kaplan c. Bulb d. Draft tube 3. water wheel a. cross flow M. Governor 1. UG 2. Digital electronic 3. Load bank october 24 Friday Friday Morning ouiz Project Development A. Permits B. Site Evaluation 1 .. Flow measurement 2. construction costs 3. Head and Power available c. Reservoir D. Dam 1. Embankment 2. concrete 3. spillway E. Intake Structures F. Penstocks or tunnels G. valves ** Fie 1d Trip to seward Hydro Dam Site (1: 00 to 3:30pm) 2 6. october 27 Monday operation A. Standard operation Procedures B. Synchronization c. Load control D. Logs, Meter Readings E. Inspections 1. oi l level s 2. Temperatures 3. Pressures 4. vibrations 5. Noise F. Housekeeping Lock out/Tag out Program G. Clearances 1. Request, write up, place, and remove 7. october 28 Tuesday ** AVTEC Plant Site Visit Hands on synchronization (2 or more times each student after demonstration by AVTEC) A. Meter readings and records B. Regular operation inspections 8. october 29 wednesday Maintenance A. Reservoir B. Dam 1. Embankment 2. concrete 3. spillway c. Intake Structures D. Penstocks or tunnels E. valves F. Turbines 1. Impulse a. Discharge chamber 2. Reaction a. Draft tube G. Governor 1. UG 2. Digital electronic H. Generator I. Excitation J. circuit Breakers K. Transformer L. switchyard 3 9. M. Distribution N. oil Tests o. Load 1. Industrial 2. Commercial 3. Residential P. Auxiliary Equipment 1. Pumps 2. Lube oil Equipment 3. Deflectors 4. Computers 5. Protective Relays 6. Metering Equipment 7. control Panels 8. Batteries a. Specific gravity b. Hydrometer October 30 Thursday seward Hvdro plant site visit A. Inspect turbine B. Generator c. valves D. Controls E. Meters F. Maintenance G. Housekeeping 10. October 31 Friday (8:30am -3:30pm) Fridav Quiz ~OMMENTS Inspections and Records A. Annual B. Federal FERC c. State safety of Dams D. Records Budget A. Annual B. Equipment Replacement c. 5 yr Replacement Programs D. Reserves ~·* NEED TRANSPORTATION TO FIELD SITES 4 · Sublimation __ , ··i:~·c~-~_;,, . Evapotr .. ,...,i!i .--~,. :~ ~:-":!..-,. Condensation Water storage in oceans - c .. .. ~ ~ c .... c c \ ._,__SOURCE (UPSTREAM COLLECTION OR SPRING) ~ PIPELINE OR PENSTOCK HICJHIEAD 11 lfiiCIUtiMlfT • Mil-Of• Sl'llOM IMSTAU.All«<l. High he•d per•i u the use of re1•tfve1y low flow regi .. s •nd use of i.pu1se turbines such •s the pe 1 ton wtleel • An lJ11Poundllent •Y be necessary for regulation of stre .. flow where se•sonal ch•nges I. 3 ,GENERATED ELECTRICITY FOR DISTRIBUTION BREAKER BOX SYSTEM---- ENCLOSURE ,, ~'====r::-- r"·~ERA TEO -~~ -. _..:CTRICITY ! FOR DISTRIBUTION GENERATOR "'~~i OUTLET/ DRAFT TUBE PIPELINE __ TURBINE .........., ............ I .. TAU.ATICII. Relattwly hfgh flow regt•• peNft the uae of a r'Netfon type propeller turbine. The eanceptua1 deatvn IIUst tnc1ude accurate head ... sur .. nts and pfpe sfztng to •fnf•tze power' 1osses. I. 2 \ \ I j \ , \ ' I I lyOr0919CtriC t-'OWer: HOW II WUJ K::S, Uv'-7v VVi::llt::l vvlt::! lvt:: lVI ..:>I.JIIvul.;:) ..,_ .::tter Science for Schools USGS Home Contact USGS Search USGS Water Basics • Earth's Water • Water Cycle • Special Topics • Water Use • Activity Center • Water Q&A • Galleries • Search this site • Help • Water glossary • Site map • Contact us • Back • Home Hydroelectric power: How it works Typical Hydroefectic Dam power plant to see the details: The theory is to build a dam on a large river that has a large drop in elevation --re are not many hydroelectric plants in "'-·•sas or Florida). The dam stores lots of water behind it in the reservoir. Near the bottom of the dam wall there is the water intake. Gravity causes it to fall through the penstock inside the dam. At the end of the penstock there is a turbine propeller, which is turned by th•~ moving water. The shaft from the turbine goes up into the generator, which produces the power. Power lines are connected to the generator that carry electricity to your home and mine. The watE~r continues past the propeller through the tailrace into the river past the dam. By the way, it is not a good idea to be playing in the water right below a dam when water is released! This diagram of a hydroelectric generator is courtesy of U.S. Army Corps of Engineers. So just how do we get electricity from water? Actually, hydroelectric and coal-fired power plants produce electricity in a similar way. In both cases a power source is used to turn a propeller-like piece called a turbine, which then turns a metal shaft in an electric generatbr Mil, which is the motor that produces electricity. A coal-fired power plant uses steam to turn the turbine blades; whereas a hydroelectric plant uses falling water to turn the turbine. The results are the same. Take a look at this diagram (courtesy of the Tennessee Valley Authority) of a hydroelectric Generator As to how this generator works, the Corps of Engineers e:<plains it this way: Turbine Blades "A hydraulic turbine converts the energy of flowing water into mechanical energy. A hydroelectric generator converts this mechanical energy into --:tricity. The operation of a generator is based on the principles discovered by Faraday. He found that , ..:'!n a magnet is moved past a conductor, it causes electricity to flow. In a large generator, electromagnets are made by circulating direct current through loops of wire wound around stacks of http://ga. water. usgs. gov/edu/hyhowworks. html 10/1/2008 lYUIVVIVVLifVI VWI'""I• ,,._,., ... ••-••"-) ---- magnetic steel laminations. These are called field poles, and are mounted on the perimeter of the rotor. The rotor is attached to the turbine shaft, and rotates at a fixed speed. When the rotor turns, it causes the field poles (the electromagnets) to move past the conductors mounted in the stator. This, in turn, causes electricity to flow and a voltage to develop at the generator output terminals." Accessibility FOIA Hydroelectric power water use ~Generators in a power plant Water Use~ Water Science home page Privacy Policies and Notices U.S. Department of the Interior 1 U.S. Geological Survey URL: http:// ga. water. usgs.gov/edu/hyhowworks. html Page Contact Information: Howard Perlman Page Last Modified: Friday, 19-Sep-2008 09:56:25 EDT http://ga. water. usgs. gov/edu/hyhowworks. htm I 10/1/2008 acts AOout Hyaropower-vvaterpower -1 n~ vvu11u ~ a...~c:auu •~::~ "~"ovwa._,,.., ..... -·::u ---··· . . . -.... .... lo •. _, rteservoirs I Hydroplants I Wisconsin River I Recreation I News I Data & Links I Public Safety I Water Levels 1 Hydropower Facts 1 FACTS ABOUT HYDROPOWER I Energy I Environment 1 Cost I Renewable 1 Recreation 1 *-'" Visit our How Hydropower Wor-ks page to learn how a hydropower plant converts the +~ power of falling water into electric energy. Energy • World-wide, about 20% of all electricity is generated by hydropower. <1 > • Hydropower provides about 1 0% of the electricity in the United States. <1 > • The United States is the second 1argest producer of hydropower in the world. Canada is num~er one. <1> . · file://E :\Projects\Facts%20About%20Hydropower%20-%20waterpower»,A,fp-%20The%2... 1 0/1/2008 ·aciS 1'-\UUUl nyut Uf.JUVVt:t -v valt:t tJUYVvl • '''"' ""'"'' ,,_." ..._..., ............ 'l::' • -~· ·-.. ~-·--· ·-· ;:JJ • Norway produces more than 99% of its electricity with hydropower. New Zealand uses hydropower for 75% of its electricity. • In the U.S., hydropower produces enough electricity to serve the needs of 28 million residential customers. This is equal to all the homes in Wisconsin, Michigan, Minnesota, Indiana, Iowa, Ohio, Missouri, Nebraska, Kansas, North and South Dakota, Kentucky, and Tennessee. (1) • In Wisconsin, hydropower accounts for 4.1% of the electric generating capacity and 4.4% of the 1 total electricity generated. <2) • Hydropower production in Wisconsin is about 2.1 billion kilowatt hours (kwh) per year. Based on a home using 8,000 kwh of energy and 2.5 people per home, this is enough energy to supply the residential needs of 650,000 people. <2) • Hydropower can come "on line" quickly to meet rapid increases in electric demand and respond to emergency energy needs. <1) Top of Page Environment • Hydropower is clean. It prevents the burning of 22 billion gallons of oil or 120 million tons of coal each year. <1) • Hydropower does not produce greenhouse gasses or other air pollution. <1) • Hydropower leaves behind no waste. <1) • Reservoirs formed by hydropower projects in Wisconsin have expanded water-based recreation resources, and they support diverse, healthy, and pr-oductive fisheries. In fact, catch rates for gamefish like walleye and smallmouth bass are substantially higher on hydropower reservoirs than natural lakes. (3 ) Too of Page file://E:\Projects\F acts %20About%20Hydropower%20-%20Waterpower%20-%20The%2... 1 0/1/2008 acts ADOUt Hyaropower -vvaterpower -1 ne vvo11u :s L~ctu11•~ "v• •c.vn .. ..,.""' ..... ·-· •:u :ost ~ydropower is the most efficient way to generate electricity. Modern hydro turbines can convert r lS much as 90% of the available energy into electricity. The best fossil fuel plants are only about 50% efficient. (1) • In the U.S., hydropower is produced for an average of 0.85 cents per kilowatt-hour (kwh}. This is about 50% the cost of nuclear, 40% the cost of fossil fuel, and 25% the cost of using natural gas. -, Average Power Production Expense per KWh I I I I I 4 ~-------------------~ 'J'--f __ --------------____ · ---! = , ,J • I € 3-j-------------------1 --i ~ }.~ r-------------------. -~ ~ 2 !----------------I I i 1.5 -i-,, ------------~ --j ~ 1 1-: ------------; --: u 0.5 t-I ----------___ , I 0 J----. -------, ---·---1 Fossil -Fueled Steam Nuclear Hydro electri c Gas Turbit1e I I I l-" Fuel M . I amtet1at1ce I • Operation 1 I I I I I I • Recent data shows that in Wisconsin hydropower is produced for less than one cent per kwh. This is about one-half the cost of nuclear and one-third the cost of fossil fuel. <2> • Hydropower does not experience rising or unstable fuel costs. From 1985 to 1990 the cost of operating a hydropower plant grew at less than the rate of inflation. <1> • Only 2,400 of the nation's 80,000 existing dams are used to generate power. Installing turbines in existing dams presents a promising and cost-effective power source. However, in the last 10 years the Department of Energy has spent $1.2 billion on research and development for other renewable sources like wind, solar, and geothermal, but only $10 million on hydropower. <1> file:J/E:\Projects\Facts%20About%20Hydropower0.420-%20Waterpower>A120-%20The%2... 10/1/2008 acts 1-\0UUl nyul UjJUWe;,l -VVOl~ltJVYYvl -I''"' .. WVII .... "' .. "" ... """ •;:, '·-· ·-•• --·--· ·-· o;;,J - Top of Page Renewable • Hydropower is the leading source of renewable energy. It provides more than 97% of all ) electricity generated by renewable sources. Other sources including solar, geothermal, wind, and biomass account for less than 3% of renewable electricity production<1> • Water is a naturally recurring domestic product and is not subject to the whims of foreign file://E:\Projects\F acts%20About%20Hydropowe,.OAl20-%20WaterpoweroAl20-%20The%2 ... 1 0/1/2008 aCtS f\OQU{ MYUI OfJOWt:l -VVi::Ut:l JJUVVt::l -I lit:: V VVIIU;:) Lvc::tUIII~ 1 "vi Jono:::uJI,_, '-'''-''l:ji 'V""'""'·· . . """"~-""--- suppliers. ('I) op of Page ~ecreation • Reservoirs formed by hydroelectric dams provide many water-based recreational opportunities including fishing, water sports, boating, and water fowl hunting. (3) • Hydro operators own a significant amount of land around many reservoirs that is open to the public for uses including hiking, hunting, snowmobiling, and skiing. <3> • Hydro operators provide many recreation facilities at their hydropower projects including boat landings, swimming beaches, restrooms, picnic areas, fishing piers, hiking and nature trails, canoe portages, and parking facilities. <3) • HydropowE~r reservoirs contribute to local economies. A study of one medium-sized hydropower project in Wisconsin showed that the recreational value to residents and visitors exceeded $6.5 million annually. <4) fop of Page =ootnotes 1. Facts You Should Know About Hydropower, National Hydropower Association, 1996 2. Wisconsin Energy Statistics, Wisconsin Energy Bureau, Department of Administration, 1994 3. Final Environmental Impact Statement-Wisconsin River Basin, Federal Energy Regulatory Commission, 1996 Lake Holcombe Recreational Use Study, Northern States Power Company, 1996 Home I Reservoirs I Hyclroplants 1 Wisconsin River 1 Recreation I News 1 Data & Links I Public Safety 1 Water Levels 1 Hydropower Facts 1 Send mail to staff@wvic.com with questions or comments about this web site. Last modified: September 07, 2004 file://E:\Projects\Facts%20About%20Hydropower%20-%20Waterpower%20-%20The%2... 10/1/2008 tsureau ot Kec1amat1on THE HISTORY of HYDROPOWER DEVELOPMENT IN THE UNITED STATES By using water for power generation, people have worked with nature to achieve a better lifestyle. The mechanical power of falling water is an age-old tool. It was used by thH Greeks to turn water wheels for grinding wheat into flour, more than 2,000 years ago. In the 1700's mechanical hydropower was used extensively for milling and pumping. By the early 1900's, hydroelectric power accounted for more than 40 percent of the! United States' supply of electricity. In the 1940's hydropower provided about 75 percent of all the electricity consumed in the West and Pacific Northwest, and about one third of the total United States' electrical energy. With the increase in development of other forms of electric power generation, hydropower's percentage has slowly declined and today provides about one tenth of the United States' electricity. Niagra Falls was the first of the American hydroelectric power sites developed for major generation and is still a source of electric power today. The early hydroelectric plants were direct current stations built to power arc and incandescent lighting during the period from about 1880 to 1895. When the electric motor came into being the demand for new electrical energy started its upward spiral. The years 1895 through 1915 saw rapid changes occur in hydroelectric design and a wide variety of plant styles built. Hydroelectric plant design became fairly well standardized after World War I with most development in the 1920's and 1930's being related to thermal plants and transmission and distribution The Bureau of Reclamation became involved in hydropower production because of its commitment to water resource management in the arid West. The waterfalls of the Reclamation dams make them significant producers of electricity. Hydroelectric power generation has long been an integral part of Reclamation's operations while it is actually a byproduct of water development. In the early days, newly created projects lackE:~d many of the modern conveniences, one of these being electrical power. This madt3 it desirable to take advantage of the potential power source in water. Powerplants were installed at the dam sites to carry on construction camp activities. Hydropower was put to work lifting, moving, and processing materials to build the dams and dig canals. Powerplants ran sawmills, concrete plants, cableways, giant shovels, and draglines. Night operations were possible because of the lights fed by hydroelectric power. When construction was complete, hydropower drove pumps that provided drainage of conveyed water to lands at higher elevations than could be served by gravity-flow canals. Surplus power was sold to existing power distribution systems in the area. Local industries, towns and farm consumers benefitted from the low-cost electricity. Much of the eonstruction and operating costs of dams and related facilities were paid for by this sale of surplus power, rather than by the water users alone. This proved to be a ,_ great savings to irrigators struggling to survive in the West. Reclamation's first hydroelectric powerplant was built to aid construction of the file://E:\Projects\Bureau%20of%20Reclamation%20History%20of%20Hydro.htm 10/1-/2008 )UI eaU Ul "t:;;\.-ICliiiClliUI I . -::::~---· - Theodore Roosevelt Dam on the Salt River about 75 miles northeast of Phoenix, Arizona. Small hydroelectric generators, installed prior to construction, provided energy for construction and for equipment to lift stone blocks into place. Surplus power was sold to the community, and citizens were quick to support expansion of the dam's hydroelectric capacity. A 4,500 kilowatt powerplant was constructed and, in 1909, five generators were in operation, supplying power for pumping irrigation water and furnishing electricity to the Phoenix area. Power development, a byproduct of water development, had a tremendous impact on the area's economy and living conditions. Power was sold to farms, cities, and industries. Wells pumped by electricity meant more irrigated land for agriculture, and pumping also lower water tables in those areas with water logging and alkaline soil problems. By 1916, nine pumping plants were in operation irrigating more than 10,000 acres. In addition Reclamation supplied all of the residential and commercial power needs of Phoenix. Cheap hydropower, in abundant supply, attracted industrial development as well. A private company was able to build a large smelter and mill nearby to process low-grade copper ore, using hydroelectric power. The Theodore Roosevelt Powerplant was one of the first large power facilities constructed by the Federal Government. Its capacity has since been increased form 4,500 kW to over 36,000 kW. Power, first developed for building Theodore Roosevelt Dam and for pumping irrigation water, also helped pay for construction, enhanced the lives of farmers and city dwellers, and attracted new industry to the Phoenix area. During World War I, Reclamation projects continued to provide water and hydroelectric power to Western farms and ranches. This helped to feed and clothe the Nation, and the power revenues were a welcome source of income to the Federal Government. The Depression of the 1930's, coupled with widespread floods and drought in the West, spurred the building of great multipurpose Reclamation projects such as Grand Coulee Dam on the Columbia River, Hoover Dam on the lower Colorado River, and the Central Valley Project in California. This was the "big dam" period, and the low- cost hydropower produced by those dams had a profound effect on urban and industrial growth. With the advent of World War II the Nation's need for hydroelectric power soared. At the outbreak of the war, the Axis Nations had three times more available power than the United States. The demand for power was identified in this 1942 statement on " The War Program of the Department of the Interior:" "The war budget of $56 billion will require 154 billion kWh of electric energy annually for the manufacture of airplanes, tanks, guns, warships, and fighting material, and to equip and serve the men of the Army, Navy and Marine Corps." Each dollar spent for wartime industry required about 2-3/4 kWh of electric power. The demand exceeded the total production capacity of all existing electric utilities in the United Stat~s. To produce enough aluminum to meet the President's goal of 60,000 new planes 1n 1942 alone required 8.5 billion kWh of electric power. file://E:\Projects\Bureau%20of%20Reclamation%20History%20of%20Hydro.htm 10/1/2008 ·Ureau of Reclamation - Hydropower provided one of the best ways for rapidly expanding the country's energy output. Addition of more powerplant units at dams throughout the West made it possible to expand energy production, and construction pushed ahead to speed up the availability of power. In 1941 , Reclamation produced more than 5 billion kWh, resulting in a 25 percent increase in aluminum production. By 1944 Reclamation quadrupled its hydroelectric power output. From 1940 through 1945, Reclamation powerplants produced 47 billion kWh of electricity, enough to make: 69,000 airplanes 5,000 ships 5,000 tanks 79,000 machine guns 7,000,000 aircraft bombs, and 31,000,000 shells During the war, Reclamation was the major producer of power in the West where needed resources were located. The supply of low-cost electricity attracted large defense industries to the area. Shipyards, steel mills, chemical companies, oil refinelries, and automotive and aircraft factories all needed vast amounts of electrical power. Atomic energy installations were located at Hanford, Washington, to make use of hydropower from Grand Coulee. Whih~ power output of Reclamation projects energized the war industry, it was also used to process food, light military posts, and meet needs of the civilian population in man~( areas. With the end of the war, powerplants were put to use in rapidly developing peacetime industries. Hydropower has been vital for the West's industries which use mineral resources or farm products as raw materials. Many industries have depended wholly on Federal hydropower. In fact, periodic low flows on the Columbia River have disrupted manufacturing in that region. Farming was tremendously important to America during the war and continues to be today. Reclamation delivers 10 trillion gallons of water delivered to more than 31 million people each year and provides 1 out of 5 Western farmers (140,000) with irrigation water for 10 million farmland acres that produce 60% of the nation's vegetables and 25% of the its fruits and nuts Hydropower directly benefits rural areas in three ways: It produces revenue which contributes toward repayment of irrigation facilities, easing the water user's financial burden. It makes irrigation of lands at higher elevations possible through pumping facilities. It makes power available for use on the farm for domestic purposes. Reclamation is second only to the Corps of Engineers in the operation of hydroelectric powerplants in the United States. Reclamation uses some of the power it produces to file://E:\Projects\Bureau%20of%20Reclamation%20History%20of%20Hydro.htm 10/1/2008 yoropower -vvJKifJ~UI~, u1t:: u t::t:: ~••v.yv.tvt-J~uta irect mechanical power transmission required that industries using ydropower had to locate near the waterfall. For example, during the 1st half of the 19th century, many grist mills were built at Saint 1857 and 1870. .r" '?nY Falls, utilizing the 50 foot (15 metre) drop in the Mississippi River. The mills contributed to lt.. ::1rowth of Minneapolis. Hydraulic power networks also existed, using pipes carrying pressurized quid to transmit mechanical power from a power source, such as a pump, to end users. ·oday the largest use of hydropower is for the creation of hydroelectricity, which allows low cost nergy to be used at long distances from the water source. "atural manifestations n hydrology, hydropower is manifested in the force of the water on the riverbed and banks of a river. t is particularly powerful when the -river is in flood. The force of the w~ter results in the removal of ;ediment and other materials from the riverbed and banks of the river, causing erosion and other 3lterations. Types rhere are several forms of water power: • Waterwheels, used for hundreds of years to power mills and machinery • Hydroelectricity, usually referring to hydroelectric dams, or run-of-the-river setups (eg hydroelectric-powered waterm ills) . . Dam less hydro, which captures the kinetic energy in rivers, streams and oceans. :Tidal power, which captures energy from the tides in horizontal direction • Tidal stream power, which does the same vertically • Vortex power, which creates vortices which can then be tapped for energy • Wave power, which uses the energy in waves Hydroelectric power Hydroelectric power now supplies about 715,000 MWe or 19% of world electricity (16% in 2003). Large dams are still being designed. The world's largest is the Three Gorges Dam on the third longest river in the world, the Yangtzi River. Apart from a few countries with an abundance of hydro power, this energy source is normally applied to peak load demand, because it is readily stopped and started. It also provides a high-capacity, low-cost means of energy storage, known as "pumped storage". Hydropower produces essentially no carbon dioxide or other harmful emissions, in contrast to burning fossil fuels, and is not a significant contributor to global warming tr-·lgh co2 . Wicket Gate Generator 0 Hydroelectric power can be far less expensive than Hydraulic turbine and electrical file://E:\Projects\Hydropower%20-%20Wikipedia, %20the%20free%20encyclopedia.htm 10/1/2008 tdropower -W1K1pea1a, me rree encyclufJt::uld hydropower resource can be measured according to the amount of available power, or energy per 1it time. In large reservoirs, the available power is generally only a function of the hydraulic head lr' -e of fluid flow. In a reservoir, the head is the height of water in the reservoir relative to its ; . .., ... after discharge. Each unit of water can do an amount of work equal to its weight times the aad. he amount of energy E releas~d by lowering an object of mass ·m by a height h in a gravitational eld is E = ·1ngh where g is the acceleration due to gravity. ,-he energy available to hydroelectric dams is the energy that can be liberated by lowering water in a ;ontrolled way. In these situations, the power is related to the mass flow rate. E rn -=-nh t t ;;1 E rn Substituting P for t and expressing t in terms of the volume of liquid moved per unit time (the rate of fluid flow¢) and the density of water, we arrive at the usual form of this expression: P= p¢gh. Fqs;.p in watts, Pis measured in kg/m 3 , ¢is measured in m 3 /s, 9 (standard gravity) is measured in rr ; and h is measured in metres. Some hydropower systems such as water wheels can draw power from the flow of a body of water without necessarily changing its height. In this case, the available power is the kinetic energy of the flowing water. 1 P = '2 p ¢ v 2 where v is the velocity of the water, or with ¢ = A v where A is the area through which the water passes, also 1 !l P=-pAv 2 ' . Over-shot water wheels can efficiently capture both types of energy. Small scale hydro power Small scale hydro or micro-hydro power has been increasingly used as an alternative energy source, especially in remote areas where other power sources are not viable. Small scale hydro power ~stems can be installed in small rivers or streams with little or no discernible environmental effect_ on JS such as fish migration. Most small scale hydro power systems make no use of a dam or major water diversion, but rather use water wheels. file://E:\Projt3cts\Hydropower%20-%20Wikipedia, %20the%20free%20encyclopedia.htm 10/1/2008 ]enerating capacity of the dam will reach 22,500 megawatts.l1l Several generators are yet to be nstalled; the dam is not expected to become fully operational until about 2011. [21 \s ···ith many dams, there is a debate over costs and benefits. Although there are economic benefits ;u\.. as flood control, clean hydroelectricity and navigation, there are also concerns about the elocation of people, siltation, loss of archaeological and cultural sites and the impact on regional :;cosy stem. [31 Contents • 1 Project history • 2 Scale of the project • 3 Economics • 4 Hydroelectricity generation and distribution • 4.1 Total generating capacity • 4.2 Generators • 4.3 Generator installation progress • 4.4 Total energy generated • 4.5 Power distribution • 5 Environmental contribution of the dam • 5.1 Direct reduction of air pollutant and greenhouse gas emission • 5.2 Reduction of greenhouse gas due to navigation • 5.3 Aforestation • 5.4 Waste management • 6 Flood control and drought relief ... 7 Navigation ' 8 Relocation of local residents • 9 Criticism • 9.1 Environmental impact • 9.2 Effect on local culture and aesthetic values • 9.3 Sedimentation • 9.4 National Security Concerns • 10 Contentious beliefs about the Three Gorges Dam project • 11 Future projects upstream • 12 Realistic appearances • 1 3 Photo Gallery • 14 See also • 15 References • 16 External links Project history The dam was originally envisioned by Sun Yat-sen in The International Development of China in 1919. [41 In 1932 the Nationalist government, led by Chiang Kai-shek, began preliminary work 'on plans for a dam in the Three Gorges. Then in 1939 the Japanese military forces occupied Yichang and surveyed the area. A design, the Otani plan, was completed for the dam in anticipation of a Japanese victory over China. [S] In 1944 involvement from the United States began when the Bureau of·~ ~clamation engineer J.L. Savage surveyed the area and drew up a dam proposal. Around 54 ...,hinese engineers were sent to the U.S. for training. Some exploration, survey, economic study, and design work was done, but the government, in the midst of the Chinese Civil War, halted work in file://E:\Projects\ Three%20Gorges%20Dam%20-%20Wikipedia, %20the%20free%20enc... 10/1/2008 - EPP-l3.0N FS 13 -r -S m a 11 Hydroelectric Plar1ts For generations water has been used as a source of · energy by industry and by a llmited number of utility companies. In the continental United States, most rivers and :.treams capable of producing huge amounts of lwdroelectric power have been harnessed; however, this does not preclude the possibility of using mini-hydroelectric power as a source of energy supply for home or farm. Harnessing < stream for hydroeleclric power is a major undertaking. Careful planning is necessary if a successful ard economical power plant is to result. State water laws and environmental concerns must be determined. Precise field data must be gathered to compare the amount of power that can be expected _from a hyd::oelectric installation to the electrical =quirements of the home or farm. Then detailed plans lhat consider both construction and maintenance can be drawn up. Perhaps the greatest mistake mude when considering small hydro::lectric installatiOns is the overestimation of a propos'.'d plant's capability. This bulletin will help you start the planning of a small power plant on a given stream of water. One of the first steps in planning is to measure the power potential of the stream. The amount of power that can be obtained from a strea :n depends on: -the amount of vvater flow the height which the ware•· fa !ls (heacl) -the effkiency of the plant to cnnvert mechanical energy to electrit:al energy_ State water laws and f'nFironmenrai c;,nccms must be determined_ Harnessing a stream for hydroelectric power is a major underraking. Stream Flow Stream flow varies greatly from season to season and depending on the nature of the terrain. A typical discharge from a 22 square mile hilly to mountainous drainage area in the Northeast during a year of normal precipitation is summarized as: M.u.irr.um Discharge \!in$mum Discharge !::========================~ 502c~ 0.5 cfs Averilg~ o,;;y ,__., z-2 f Disch~trge ,............ :J · c !> ~!•dian Discharge' p 3.~ cfs WATER FLOW. Cubic feot per Se<ond (cfsl' 'Flow l> 8.< cfs or less For 183 days or h<'lf the year. '! cubic foot per second ; <149 gallons per r11lnute. The smallest commercially manufactured hydroelec- tric power plant at one-half kilowatt (KW) or 500 walls needs i.1 cfs \Vith a 12' height of watr:r fall or head. Therefore no power can be generaterJ during low-flow periods withom reservoir storage. It is also imeresting to look at the peak now. r\ te-n-kilowatt hydroelectric plant needs 16.3 cfs with a 12· head. leaving a subslanrial part of the peak flow to be contendE>d wHh--not <-1 simple t<Jsk. This extre111c V<c'riatiorc i!lustrales the value of a resep:oir ro regulaw and even the. f1ow. IMPULSE TURBINE The type of facility you_ wish to provide wilh eiecLrical service will largely determine wllelhc;· you use an Alternating or Direct-Current generator. Lights and the universal motors that uperate smatl appliances and tools vvill operate on DC. ~arger motors, TV's and many appliances require AC to operate. Alternating Current may be transmitted greater distances and on smaller wires than is possible with Direct Current: however. an AC installation does require an extra i:1vestment in governing equipment. Direct Current generators are usually less expensive '1an AC generators but they do require expensive 1verters to convert to AC. The potential of storing DC ''1 batteries during low-usage periods and at times of ,even water flmN is a compensation of such a system. Selected Causes of Failure The main reasons for lack or success with small water pov,:er developments are: Failure to realize hovv important full field daw is for proper design. 2. Failure ot hcrnemade equipment made with junked parts. 3. Over estimating the amnunl and constancy uf the ~rream flow. 4. Penstocb or flumes that are too small to allovi the plant to operale at full capacity. 5. Failure to anticipate the expense of keeping trash racks clear and machinery in good repair. 6. Failure to design and plan for winter ice buildup. 7. Overestimation of a proposed plant's capa bility. The average home has demand peaks varying from '1 to 12 kilmvatts. References Design af Smail Dams. u.S Department of Interior. Supt. of Documems. U S. Government Priming O!lke, Washington DC 20402 T!H_~ Ponds for \Nater Supply and Recreation. Agrk. Handbook No. 387. Soil Conservation Service. USDA "Your 0\vn Wate:-Power Plant". Popular Science. HJ47. Reprinted in issuE's no 13 and !4 .Mother Earlil News. 'VVatr•r Power for Your Home". PrJpular Science . .tvfay !977 North>',1:>t He,si(;na1 Agn\.'uUur<-d th~o: Nm·u,_c;::L'H L.HFI Gr:mt Agricu!turt:. Ur:h:crsit~l r.:-Connecticut L l cf 0-·l<:~mr-Z Ur::ve1s.it'.; of : ... 1arvktnd of tvlassachusetts N<:.•v; 1-l::~mps~un; Univt""'rSit)' Z Cnrnell Un.fversi~y Un;vf:rsity Z Udv('L'iif",· 'L t~mversity of \'ermL'Ilt • ~.Ve.st Virg!nU University FS-!::\ Nov '7R l OJ\1 ..,. ··JI'., I .!ill ... , ..:·!- ;-: .. -- PropeltJ If Alaska Vocatioaal Tech. Center MAINTENANCE TRAINING BASIC ELECTRICITY REVIEW f i I ISSUED TO: ________ _ DATE: __________ _ CHECKED BY: __ --;:-.----~ DATE : _________ _ Copyript 1980 by NUS Tralnlng Cocporatlon 910 Clopper Road Galt.bersburg, Maryland 20878 (800) 84&-1717 (30l) 2.5&-2500 All rights reserved.. This book or any part thereof must not be reproduced in any form without the written permission of NUS Training Corporation. Printed in the United States of America September, 10, 19&0 Revised September 30, 1986 TABLE OF CONTENTS Section Title Page 1. Where Ooes Electricity Coo1e From?............... 1-1 1.1 Electricity and the Atom........................ 1~1 1.2 Sources of Electricity.......................... 1-3 .2. Basic Electrical Quantities..................... 2-1 2.1 Current .•............•....•.............• ,',..... 2-1 2.2 Voltage......................................... 2-1 2.3 Resistance...................................... 2-2 2.4 Ohm 1 S Law .................. ,. ............ t............. 2-2 2.5 Power .................. ~ ............ , ........... ,..... 2-8 .,.., 3. Series and Parallel Circuits.................... 3-1 3.1 Series C1rcuits............................ ..... 3-1 3.2 Parallel Circuits............................... 3-6 -3.3 Resistor Color Codes............................ 3-10 4. £1 ectromagnet ism......................... . . . . . . . 4-1 4.1 Induction ....................................... 4-1 4.2 Transformers.................................... 4-3 5. Inductance and Inductors........................ 5-l 5.1 Self-Induction.................................. 5-1 5.2 I nduc t a nee ............. , . . . . . . . • . . . . . . . . . . . . . . . . 5-2 5.3 Inductors....................................... 5-7 6. Capac Hance and Capacitors........... .. .. .. .. .. . 6-1 6 .! Capacitance .•...•.•••..••••..••••••.•....•.•.••• 6-1 6.2 Capacitors...................................... 6-1 6.3 Types of Capacitors............................. 6-3 6.4 Hazards of Capacitors........................... 6-6 APPENDIX A: COLOR CODES App. A-1 1-1 1-2 1-3 1-4 2-1 2-2 2-3 2-4 3-lA 3-18 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 4-1 4-2 4-3 4-4 5 1 5-3 5-4 5-5 5-6 5-7 LIST OF ILLUSTRATIONS Structure of the Hydrogen A tom ................. . T hermocoup 1 e ................................... . T yp i cal Battery ..••........••.••................ U<oing Magnetism to Produce Electricity ......... . Simple c'ircuit. ...•.•..•...•••..•....•••.•....•. Simple Circuit: Unknown Voltage ................ . Simple Circuit: Unknown Resistance ..........•... Current Paths and Resistance ..••...••••.•.••.•.. Series Circuit .....•.......•...••.•••.••..•.••.• Par a 11 e 1 C i rc u i t ............................... . CalculaUng Current in a Series Circuit. ....... . Calculating Resistance in a Series Circuit .•.... Series Circuit with One Resistor ............... . Calculating Voltage Drops in a Series Circuit .. . Parallel Circuit with Three Current Paths .....•. Calculating Current in a Para11el Circuit ....... Resistance Value Printed on a Resistor •.••...... Color-Coded Resistor •...•.•.........•.........•. Inducing Vo 'I tage •••.•..........•...•.•........•• Parts of a Typical Transformer ................. . Step-Up Transformer ..................•.•.....••. Step-Down Transformer .......•...•..•.•.......... Current Flow with No Self-Induction ............ . Current Flow with Self-Induction ....•••••••.••.. Magnetic Lines of Force in a Straight Conductor. Inductance in a Coiled Conductor .............. .. Conductor Coiled Ar-ound a l\1etal Cor-e ........... . Arcing Switch •.•..•.....•••.•..•....•.•••....•.. Inductors ••..............•..•.•..•.....•...•.•.• i i 1-2 1-4 l-5 l-6 2-3 2-4 2-5 2-7 3-1 3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-10 3-11 4-2 4-3 4-4 4-5 5 2 5-2 5-3 5-4 5-5 5-6 5-7 Figure 6-1 6-2 6-3 6-4 6-5 6-6 Title Basic Parts of a Capacitor ..................... . Charged Plates on a Capacitor .................. . F 1 at 0 isc Capacitors •.... , ..................... . Oil-Filled Capacitor •...•..••.•••.•.......•..... Electrolytic Capacitor ......................... . V ar i ab 1 e C apa~ i tor ...•..............•.......•..• i i i 6-1 6-2 6-3 6-4 6-5 6-5 BASIC ELECTRICITY REVIEW Modern industrial plants contain a great deal of electrical equipment that needs to be maintained and repaired. To perfonn electrical maintenance tasks correctly and efficiently, electricians and electrical maintenance personnel must have (1) a basic understanding 9f the fundamentals of elec- trical theory; (2) a specific knowledge of the way electrical devices oper- ate; and (3) practical hands-on experience. Basic Electricity Review reviews the fundamental principles of electrical theory as applied to electrical circuits and devices such as transformers, inductors, and capacitors. The general topics covered in this unit include the nature of electricity; basic electrical quantities and their units of measurement; electrical circuits; and electromagnetism. 1. Where Does Electricity Come From? OBJECTIVES: • Describe the structure of an atom. • State the three characteristics of electrical charges. • List six major sources of electricity. 1.1 El ectr i citv and the A tom Electrical theory is founded in the theory of the structure of matter. The ... tenn matter is used to describe anything that has weight and occupies space. Matter exists in one of three forms: liquid, solid, or gas, and it can be identified and measured. All matter is composed of atoms. tHorns are the key to understanding electricity, because atoms con- tain electrically charged particles. For example, the hydrogen atom, represented in Figure 1-1, contains one p;oton, which is positive1y charged, and one electron, which is negatively charged. 1-l - BASIC ELECTRICITY REVIEW 1. Where Does Electricity Come From? (continued) All atoms contain protons and electrons. Protons are always located in the center of the atom, an area called the nucleus. Electrons orbit around the nucleus, similar to the way in which planets in the solar system orbit around the sun. Protons are always positively charged, and electrons are always negatively charged, but the value of each charge is the same. In other words, if a proton has a charge of +1, then an electron has a charge of -1. There are three important facts to remember about electrical charges: {1) Opposite electrical charges of equal value cancel each other out. (2) Opposite electrical charges attract each other. (3) like electrical charges repel each other. A proton and an electron cancel each other out, because a +1 charge cancels out a -1 charge. Therefore, when an atom contains an equal number of protons and electrons, the opposite charges cancel each other out, making the atom electrically neutral. 1-2 ) BASIC ELECTRICITY REVIEW 1. Where Does Electricity Come From? (continued) Because opposite charges attract each other, an atom tends to retain the general structure shown for the hydrogen atom in Figure 1-1. The nega~ tively charged electrons keep orbiting around the nucleus because they are attracted to the positively charged protons. A particle thai is orbiting around another tends to move away from the second particle unless it is prevented fr·om doing so. The attraction between the electron and the nucleus keeps the electron in orbit around the nucleus. Under certain circumstances, it is possible to remove some electrons from their orbits. A source of energy is required to detach electrons from their orbits, and a steady supply of energy is necessary to keep the detached electrons moving. The movement of electrons is what the tem1 electric current actually refers to. 1.2 Sources of Electricity There are six basic sources of energy that can be used to detach electrons from their orbits and sustain electric current. They are {1) friction, (2) heat, (3) pressure, (4) light, (5) chemical action, and {6) magne- tism. Friction, heat, pressure, and light are used primarily in specia- lized applications. Chemical action and magnetism are more commonly used to produce large amounts of electricity for general use. Friction is the rubbing of one material against another. The rubbing causes electrons to leave one material and move to the other. As the electrons are transferred, a positive charge builds up on the material that is losing electrons, and a negative charge builds up on the material that is gaining electrons. The type of electricity produced by friction is called static electricity. Static electricity is more often a nuisance than a useful source of electricity. 1-3 BASIC ELECTRICITY REVIEW 1. Where Does Electricity Come From? (continued) A thermocouple is a common example of an electrical device that uses heat as its source of energy. The design of a thermocouple is based on the fact that heat will cause a small amount of electricity to move across the junction of two d1ssim11ar metals. A thermocouple is illustrated in Figure 1-2. The two metals in this particular thermocouple are copper and iron. Heat energy applied at the junction of the wires causes electrons to leave the copper wire and move to the iron wire. This movement of elec- trons is electric current, which can be measured. The amount of current flow is related to· the temperature at the junction of the wires. Pressure can be applied to certain types of crystals to produce electri- city. The application of pressure to such crystals releases electrons from their orbits and thus causes current to flow. Some types of pressure measuring devices make use of this effect. 1-4 ... ·.<i :. .. 1 ,_., BASIC ELECTRICITY REVIEW 1. Where Does Electricity Come From? (continued) In some materials, ..l..!.9!:!l can cause atoms to release electrons. When this happens. current flows through the material. This current, produced by what is called a photoelectric effect, can be used to operate devices such as those that control the operation of street lights. Daylight shining on spec i a 1 materia 1 in this type of device produces a sma 11 current. The current operates a switch that shuts the light off in the morning. As long as there is current through the s~itch, the light remains off. At night- fall, there is no light to produce the current, so the light comes on. Chemical action is one of the most.· comnon sources of energy used to produce electricity. Certain types of chemical reactions create electricity by separating the positive and negative charges in atoms . Batteries (Figure 1-3) depend on chemical reactions to produce electricity. 1-5 BASIC ELECTRICITY REVIEW 1. Where Does Electricity Come From? (continued) Magnetism is the major source of energy used to produce electricity in large quantities, because it is the most practical method. Generators use an effect of magnetism called magnetic induction to produce electric cur- rent. Magnetic induction is the generation of electric current 1n a conductor due to the relative motion between the conductor and a magnetic field. For example, if a conductor is moved between the poles of a magnet, electrons will flow through the conductor. as shown in Figure 1-4. r .. ---... ----~----------~--------------·-__ ...... . \ l \ I I DIP.ECTIO~ Of MOV~MrNT ~lovRe 1-t/ lhlf.lC. ~Net")"' -to P~ov\Jc t Gl€CO:.\Crr'f 1-6 ~. BASIC ELECTRICITY REVIEW 1. Where Does Electricity Come From? (continued) Questions 1-l. Name two subatomic particles that have an electrical charge. a. b. 1-2. True or False. A proton has a negative charge; an electron has a positive charge. 1-3. Opposite electrical charges (a) each other. Like (attract, repel) electrical charges (b) each other. {attract, repel) 1-4. Circle the correct answer. Electric current is the movement of a. Protons b. Electrons c. Atoms d. None of the above 1-5. List the two major sources of energy used to produce large amounts of e 1 ec t r i c ity . a- b. 1-7 BASIC ELECTRICITY REVlEW (continued) 2. Basic Electrical Quantities OBJECTIVES: • Explain what current, voltage, and resistance are. • Describe the way in which current, voltage, and resis- tance are related. • Define the terms watt and watt-hour. 2.1 Current As stated in Section 1, electrical current is the movement, or flow, of e 1 ec trons. Current is measured in units called amperes. An ampere ac- tually refers to the rate of flow of electrons. One ampere is the flow of 6.28 X 10 18 electrons past a given point in one second. There are two types of current: direct current and alternating current. Direct current (DC) flows in only one direction. The flow of electrons in a DC circuit is similar to the flow of water in a piping system. Alter- nating current (AC) reverses direction as it flows. The electrons in an AC circuit flow back and forth continuously. Direct current is used to explain most of the concepts In this unit because direct current is easier to illustrate and to understand. In general, the concepts covered can be appl1ed to alternating current as well, with some minor variations, which will be noted when they are applicable. 2. 2 Vo 1 tage Voltage is the driving force that makes electrons flow. Voltage is mea- sured in units called volts. The voltage source in an electric circuit is similar to the pump in a piping system. The voltage source pushes elec- trons through the circuit in much the same way that the pump pushes water through the pipes. In indus:.r.i.al.f.ilrilities two co11111on sources of voltage are batteries and generator • BASIC ELECTRICITY REVIEW 2. Basic Electrical Quantities (continued) 2.3 Resistance Resistance is the electrical quantity that opposes electron flow in a c1rcuit. Resistance is measured in units called ohms. An ohm is defined as the amount of resistance that allows one ampere of current to flow in a circtJit when there is one volt of force pushing the current. All materials offer some resistance to current flow. The materials most often used in the manufacture of electrical equipment are generally class- ified as either insulators or conductors, depending on the ~mount of resis- tance they provide. Insulators offer a great deal of resistance to current flow, while conductors offer very little resistance. 2. 4 Ohm's Law The relationship between current, voltage, and resistance was described by George Simon Om1 in a form that is commonly referred to as Ohm's Law. Ohm's Law states that current is equal to voltage divided by resistance. This law is often expressed using symbols for each quantity. The lette1· I is used to represent current. E represents voltage, and R represents E resistance. Using these syrnbols, Ohm's Law can be expressed as I : R. The form of Ohm's La1~ can be changed to show two other aspects of the relationship between current, voltage, and resistance. The first of these is that voltage equals current times resistance, orE IR; and the second is that resistance equals voltage divided by current, orR=~· Ohm's Law can be used in the appropriate form to determine one quantity ( cunent., voltage, or resistance) in an electrical circuit if the other two are kno\~n, or to predict the effect that a change in one quantity will have on another. Figure 2-1 shmvs a simple electrical circuit. The circuit contains a voltage source, which: in this case, is a battery; a load, or resistance, which is a light bulb; and a switch, which, when closed, makes the circuit a complete palti -through which current can flow. ~~<, • ~ 2-2 ~-'"( BASIC ELECTRICITY REVIEW 2. Basic Electrical Quantities (continued) Example 2-1: Using Uhm's Law to Calculate Current To determine the amount of current in the circuit shown in Figure 2-1, the values for voltage and resistance must be known. This circuit contains a 12-volt battery, so E = 12 volts. The resistance of the light bulb is 24 ohms, so R "'24 ohms. (In any circuit, there is a certain amount of additional resistance present in the wiring and in other components, like the switch, but, in this example, the amount of this additional resistance is negligible.) Current is calculated by using Ohm's Law in the following form: I =I R Substituting the known values: 1 _ 12 vo 1 ts -24 ohms Therefore: I = , 5 amps 2-3 BASIC ELECTRICITY REVIEW 2. Basic Electrical Quantities (continued) Example 2-2: Using Ohm's Law to Calculate Voltage Figure 2-2 shows a schematic representation of a simple circuit in which the values for current and resistance are known. There is one amp of current flowing through the circuit, so I ~ 1 amp. The resistance of the circuit is 9 ohms, so R = 9 ohms. To determine voltage, Ohm's Law is used in the following form: E "' IR Substituting the known values: E = 1 amp x 9 ohms Therefore: E "' 9 volts 2-4 BASIC ELECTRICITY KEVIEW 2. Basic Electrical Quantities (continu~d) Ex~nple 2~3: Using Ohm's Law to Calcu1ate Resistance Figure 2~3 shows a simple circuit in which the values of current and voltage are known. The current flowing through the circuit is one ampere, so I = 1 amp. The circuit contains a 6-volt battery, so E = 6 volts. To determine resistance, Ohm's Law is used in the following form; r: R "T Substituting the known values: R : 6 volts 1 amp Therefore: R = 6 ohms As stated earlier, Ohm's Law can also be used to predict the effect that a change in one quantity (current, voltage. or resistance) will have on another. For example, Ohm's Lav1, in the i =~form, states that current is directly proportional to voltage and inversely proportional to resistance. Therefore, if resistance does not change, an increase in voltage produces an increase in current -and a decrease in voltage produces a decrease in current. Similarly, if voltage does not change. an increase in resistance produces a decrease in current, and a decrease in resistance produces an increase in current. 2-5 BASIC ELECTRICITY REVIEW 2. Basic Electrical Quantities (continued) For example, as.sume the fo1lowing initial conditions: Voltage (E) = 100 volts Resistance (R) • 10 ohms Current (1) ; 10 amps 1f the va1ue of voltage (E) decreases from 100 volts to 50 volts while resistance (R) remains constant, current (I) will decrease: -E -R _ 50 volts -10 ohms = 5 amps If the value of voltage (E) increases from 100 volts to 200 volts while resistance (R) remains constant, current (I) will increase: E R _ 200 volts ·-10 ohms ::: 20 amps With the same initial conditions, E = 100 volts, R = 10 ohms, ana I 10 amps, if the value of resistance (R) increases from 10 ohms to 20 ohms while voltage (E) remains constant, current (I) will decrease: E ]'{ , 100 VO 1 tS 20 ohms. 5 amps 2-6 - •"'·• BASIC ELECTRICITY REVIEW 2. Basic Electrical Quantities (continue~) If tile value of resistance (f<) decreases from 10 ohms to 5 ohms while voltage (E) remains constant, current (I) will increase: - E -R = 100 vo 1 ts 5 ohms 20 amps The effect that a change in resistance has on cui·rent is particularly evident in open circuits and short circuits. As stated earlier, a circuit (Figure 2-4A) is a complete path through which current can flow. If the path is interrupted, such as by opening a switch (Figure 2-48), current can no longer flow through it. In an open circuit, the resistance is so great that there is no current f 1 ow -when resistance increases, current de- creases. A short circuit (Figure 2-4C) occurs wnen the resistance in a circuit, or part of a circuit, drops to almost zero. Minimum resistance means maximum current flow. Short circuits can be dangerous. High current produces intense heat in a conductor, and that heat can damage power sources, burn the insulation on wiring, and start fires. A. Complete Circuit 1 l LJ B. Open Circuit 2-7 C. Short Circuit BASIC ELECTRICITY REVIEW 2. Basic Electrical Quanti ties (continued) 2.5 Power Power is defined as the rate at which work is done. In an electrical circuit, power is calculated by multiplying voltage times current. Using symbols, the formula for calculating power is P = El. Power is measured in units called watts. One watt is defined as the amount of power produced when one volt causes one ampere of current to flow. Electrical devices are usually rated for both voltage and power. The power rating on an electrica<l device indicates how much electric power the device can convert into other forms, such as heat and light, l'tithout being damaged. Power ratings are important. If an electrical device is operated so that it receives more power than it. is raterl for, the excess power is converted to heat, and the device overheats. The watt-hour is the basic unit used to measure electrical energy. Watt- hours are determined by multiplying power by time. One watt~hour is the amount of electrical energy used when one watt of power is delivered to an electrical device for one hour. Because the watt-hour is a fairly small unit of energy, the kilowatt-hour is often used instead. One kilowatt-hour is equa1 to one thousand watt-hours. The kilm ... att-hour is the unit that electric utilities use to determine how much energy their customers have used during a billing period. 2-1. Current is measured in units called --------------------- 2~2. True or False. Direct current reverses direction continuously as it flows through a circuit. 2-3. True ot· False. Voltage is the driving force that causes current flow. 2-4. Voltage is measurer! i.n units called ·-·--·-··-···------~-------- 2-5. Resistance the movement of electr·ons. (accelerates, opposes) 2· 8 BASIC ELECTRICITY REVIEW 2. Basic Electrical Quantities (continued) 2-6. Circle the correct answer. Materials that offer little opposition to electron flow are called: a. Insulators b. Conductors c. Resistors d. None of the above 2-7. Resistance is measut'ed in units called 2-8. State the meaning of each of the following symbols: 1 E R 2-9. List three ways that Ohm's Law can be written using the symbols I, E, and R. a. b. c. 2-10. True or False. If val tage remains constant, Ohm's Law can be used to predict the effect that a change in resistance will have on current. 2-11. In a shod circuit, resistance is (a) , and current is (b) (high' low) (high, low) 2-12. Power is calculated by multiplying (a) times (b) ------------------------- 2-13. PowE!r is measured in units called 2·· 9 BASIC ELECTRICITY REVIEW (continued) 3. Series and Parallel Circuits OBJECTIVES: • Describe the difference between a series circuit and a parallel circuit. • Explain now current, voltage, and resistance are calcu- lated in series circuits and in parallel circuits. As stated earlier, a circuit is a path through which cur-rent can flow. There are two basic types of circuits: series circuits and parctllel circuits. A series circuit (Figure 3-lA) has a single current path. The components in a series circuit ar·e connected end to end. A parallel circuit (Figure 3-lB) contains two or more parallel paths through which CLlt'rent car1 flow. Tne components in a parallel circuit are connecteu siue by side. 3.1 Series Circuits J\11 of the devices ir1 i: series circuit must be either on Ol' off at the same time, because a series circuit contains only one path through which current can flow. A break in the current path of a series circuit interrupts the entire circuit. 3- BASIC ELECTRICITY REVIEW 3. Series and Parallel Circuits (continued) There are four basic facts that apply to the behavior of current, voltage, and resistance in a series circuit: {1) The amount of current flowing tl1rough each component is ttJe same; (2) the sum of the individual source voltages equals the total applied voltage; (3) the sum of the individual resistances in the circuit is equal to the total circuit resistance; and { 4) the total applied vo 1 tage in the circuit is equal to tile sum of the voltage drops across the resistors in the circuit. These facts and Ohm's Law can be used to analyze series circuits as shown in the following examples: Example 3-1: Calculating Lurrent in a Series Lircuit The circuit shown in Figure 3-2 is a series circuit. Therefore, the same amount of current flows through each component. The current in this cir'cuit can be calculated using Ohm's Law in the form I "ft• current equals voltage divided by resistance. I:::? (:;I~ JOJL In a series circuit, the sum of the individual voltages i:, equal to the applied voltage, so, in this example: E ::: E1 + E2 Substituting known values: E ~ 9 volts ~ 3 volts Therefore: E = 12 volts 3-2 BASIC ELECTRICITY ~EVIEW 3. Series and Parallel Circuits (continued) In a series circuit, the sum of the indiv1dual resistances is equal to the total circuit resistance, so, in this example: Substituting known values: R = 10 ohms + 20 ohn~ + 30 ohms Therefore: R = 60 ohrns Now, the total values for voltage and resistance can be use6 to calculat~ the current in the circuit: E = R 12 volts 60 ohms " .2 amps Example 3-2: Calculating the Value of a Resistor in a Series Circuit In the series circuit sho~>m in Figure 3-3, tile voltage source produces 24 volts, and the value of the cun·ent flowing U1rougn tl1e circuit is .2 amps. The values of two of the resistors are known: R1 is 20 ohms and R2 is 40 ohms. The value for R3 must be calculated. 3-3 BASIC ELECTRICITY REVIEW 3. Series and Para1le1 Circuits (continued) Since the total resistance in a series circuit is equal .to the sum of the individual resistances: R = Rl + R2 + R3 Substituting known values: R = 20 ohms + 40 ohms + R3 Adding known values: R ~ 60 ohms + R3 Now, the known values for voltage and current can be used to calculate first the total resistance in the circuit and then the value of the unknown resistor: R - £ - T 60 ohms + R3 = 24 volts .2 amps 60 ohms + R3 = 120 ohms R3 = 60 ohms Example 3-3: Calculating the Voltage Drop Across Resistors in a Series Circuit A voltage drop is the amount of voltage across a resistor in an electrical circuit. In a series circuit containing a single resistor (figure 3-4), the voltage drop across the resistor is equal to tne total applied voltage in the circuit. In a series circuit with two or more resistors, the voltage drop across each res1stor is always directly proportional to the resistance of that resistor. The sum of the voltage drops in a series circuit is always equal to the total applied voltage in the circuit. T I~ ~<.le.;.. U~i:u\1 f.!IU\ C-t f:t.76lot_ 3-4 ;-::" BASIC ELECTRICITY REVIEW 3. Series and Parallel Circuits (continued) To determine the voltage at'OP across each of tile res1stors in Figure 3-5, Ohm's Law can be used in the form E" IR, voltage equals current times resistance. The value used for 1 is the total current, because the current flowing through each component in a series circuit is the same. In this circuit, tr1e value for is .2 amps. The value for' each resistm- (R1, R2 and R3 ) is given in Figure 3-5. ~~ ~zosL. l~f1-----l Q3 ::.lcC»L C./llcul.-41if\{1\[·Lr,.J;,f Lfl,;of;. ~rJ A Sfl·l;·.::. ('lr.l.:', •. q The voltage drop across R1 is calculated as follows: E l IR l E1 ( .2' arnps) (20 ohms) E1 ~ 4 volts The voltage drop across R2 is: E2 lR 2 E2 (.2 amps) (40 ohms) E2 8 volts Ancl for R3: c !R3 \._3 E 3 (. 2 amps) (60 ohms) E3 12 volts 3-5 -· BASIC ELECTRICITY REVIEW 3. Series and Parallel Circuits (continued) In each case. the voltage drop across the resistor is directly proportional to the value of the resistance. When the voltage drops across all three resistors are added, their sum is equal to the total applied voltage. According to Figure 3-5, the total applied voltage in this circuit is 24 volts. E = El + Ez + £3 £ = 4 volts + 8 volts + 12 volts E 24 volts 3.2 Parallel Circuits Parallel circuits always contain two or more paths, or legs, through which current can flow. The circuit shown in Figure 3-5 has three current paths. In a parallel circuit. it Is possible to switch the current off in one or more legs without interrupting the flow of current through the remainder of the circuit. The amount of current flowing through each leg of the circuit varies according to the resistance in that leg. 3-6 BASIC ELECTRICITY REVIEW 3. Series and Parallel Circuits (continued) There are three basic facts that apply to the behavior of current, voltage, and resistance in a parallel circuit: (1) The total circuit current is equal to the sum of the currents flowing through each leg; (2) the total circuit resistance is less than the resistance in any single leg; and (3) the voltage drop across each leg of a parallel circuit is equal to tt1e source voltage. These facts and Ohm's Law can be used to analyze parallel circuits as shown in the following examples: Example 3-4: Calculating Total Current in a Parallel Circuit-Method I One way to determine the total amount of current flowing through a parallel circuit such as the one shown in Figure 3-7 is to use Ohm's Law in the form I = ft• witn E and R referring to total voltage and total resistance, respectively. In the circuit shown in Figure 3-7, the source voltage is 120 volts, so the value for E is 120 volts. Values are given for each resistor in the circuit, but tt1e value for total circuit resistance must be calculated. This calculation involves Ohm's Law and the fact that the total current in a parallel circuit is equal to the sum of tr1e currents in all the legs. According to Ohm's Law, current is equal to voltage divided by resistance: E -R 3~ 7 BASIC ELECTRICITY REVIEW 3. Series and Parallel Circuits (continued) Total current in a parallel circuit= sum of currents in each leg Substituting~ for !, since current is unknown: + E + E n-2 n-3 Since the voltage in each leg of a pat'allel circuit is equal to the source voltage, the equation can be simplified by multiplying each part by t· Then: 1 1 -= -t R Rl Substituting known resistance values: 1 R 1 30 ohms + 1 40 ohms Working out the math: 1 -8 R-rnJ R = 15 ohms Now, v1ith the total voltage and the total resistance known, the total current in the circuit can be calculated, as follows: = ~ I = 120 vo 1 ts 15 ohms = 8 amps Example 3-5: Calculating Total Current in a Parallel Circuit -Method 2 Since the total current in a parallel circuit is equal to the s~m of the currents flowing through all the legs, the total current in the circuit 3-8 BASIC ELECTRICITY REVIEW 3. Series and Parallel Circuits (continued) shown in Figure 3-7 can also be determined by calculating the current in each leg separately and then adding the results. Ohm's Law can be used on each leg of a parallel circuit the same way that it is used to analyze series circuits. Thus, to calculate the current in each leg of a parallel cir'cuit, Ohm's Law is used in the form: Since the voltage across each leg of a parallel circuit is equal to the source voltage, the value for E in this circuit is always 120 volts. The resistance in each leg is different, so the current in each leg is dif- ferent. In the first leg, the current fs calculated as follows: Il E "' I< 1 11 120 volts 30 ohlns 11 = 4 amps In the second leg: I - E 2 -ll2 1 _ 120 vo 1 ts 2 -40 ohms And in the third leg: E ll3 l 120 YO lts 3 "' 120 ohms I 3 = 1 amp 3-g BASIC ELECTRICITY REVIEW 3. Series and Parallel Circuits (continued) Now, the total current in the circuit can be determined by adding the currents through all three legs. =: Il + 12 + 13 4 amps + 3 amps + 1 amp 8 amps The total current through the circuit shown in Figure 3-7 is 8 amps. Both the method given in Example 3-4 and the method giveri in Example 3-5 produce the same answer. Either method can be used to determine the total current in a parallel circuit. 3.3 Resistor Color Codes Resistors are components that are put into circuits to reduce current flow. They acc001plish their purpose without drastically changing either the physical size of a circuit or the materials used to make it. The amount of resistance that a resistor provides is measured in ohns. All resistors have their resistance value indicated on them in some way. On some resistors, especially the 1 arger ones, numbers are printed on the surface of the resistor. The resistor shown in Figure 3-8, for example, has a resistance of 20 ohms. 3-10 r• 't BASIC ELECTRICITY REVIEW 3. Series and Parallel Circuits (continued) With smaller resistors, It is not always practical to have numbers printed on the resisto1· surface. The problem of identifying small resistors has been solved by the use of a color code. A series of colored bands around the resistor· (Figure 3-9) indicates its resistance value. The standard color code is explained in Appendix A to this text. Questions 3-1. A circuit contains a single current path; the ( s er i es, para 11 e 1 ) cornponents in the circuit are connected end-to-end. 3 " -c. A circuit contains two or mm·e current paths; the {series, paralleT) components in the circuit are connected side by side. 3-3. A bt'eak in the current path of a rupts the entire circuit. (series, parallel) circuit inter- 3-4. True or Fa1se. The two major differences between series and paral1e1 circuits are (1) the ways in which they are arranged; and (2) the way in which current, v<J 1 tage, and resistance behave. 3-11 BASIC ELECTRICITY REVIEW 3. Series and Parallel Circuits (continued) 3-5. Circle the letter of each characteristic that applies to a series circuit: a. The amount of cur'rent flowing through each component in the circuit is the same. b. The current in each leg of the circuit may be different, de- pending on the resistance in that leg. c. The sum of the individual source voltages equals the total applied voltage. d. The sum of the resistances of all resistors in the circuit equals the total circuit resistance. 3-6. True or False. The amount of current flowing through each leg of a parallel circuit varies depending on the amount of resistance in the 1 eg. 3-7. True or· False. It is possible to turn off the current in some of the legs of a parallel circuit without interrupting the flow of current to other 1 egs. 3-8. Circle the letter of each characteristic that applies to parallel circuits: a. The amount of current flowing through each leg of the circuit is equal to the total circuit current. b. c. d. The total resistance in the circuit is always greater than the resistance in any ~ingle leg. The voltage drop across each leg in the circuit is equal to the source voltage. The sum of the currents in each leg is equal to the total circuit current. 3-12 f'·•· J.J. (!!; BASlC ELECTRICITY REVIEW (continued) 1\. ~}ectrornagnetl sm OBJECTIVES: • Define electromagnetism. 1 Describe the effect of a changing magnetic field on a conductor. • Define induction. t Describe how a transformer is constructed. Magnetism and e1ectricity are closely related. Magnetism is a major source of electricity, and electricity is also a source of magnetism. As stated in Section 1, it is possible to produce electricity with a magnetic field, a conductor, and relative motion. This section concentrates on how a magnetic field can be produced by electric current flowing through a con- ductor. Electromagnetism is magnetism that is created by current flowing through a conductor. The field that builds up around the conductor due to the flow of e1ectric current is called an electromagnetic field. An electro- nagnetic field is only present when current is flowing. It does not appear or disappear instantaneously-it builds up or collapses over a period of time. This happens very quickly; it usually takes only a fraction of a second, but t t does take time. Any change in the flow of cur-rent tht·ough a conductor causes a change in the electromagnetic field around the con~ ductor. When the flow stops, the magnetic field collapses. When the f1ow starts, the magnetic field builds up. 4.1 Induction Whenever there is relative motion between a magnetic field and a conductor, a voltage is created in the conductor. This process is called induction. The motion may be provided by movement of the conductor or movement of the magnetic field. When a changing magnetic field is produced by sending a. 1 N BASIC ELECTRICITY REVIEW 4. Electromagnetism (continued) current through a conductor, that field can be used to produce voltage in another conductor. Induction only occurs when the magnetic field is either building up or collapsing. The building up or collapsing of the magnetic field provides the necessary relative motion. Figure 4-1 shows conductors A and B placed side by side. When current is sent through conductor' A, an electromagnetic field builds up around that conductor. The magnetic lines of force that make up the field around conductor A cut across con due tor B and induce a vo 1 tage there, causing current to flow through conductor B. The voltage induced in conductor B only exists while the electrcrnagnetic field around conductor A is changing. As soon as the electromagnetic field becomes constant, voltage is no longer induced in conductor B, because there is no longer any motion. I ' ""',.r "~, _.-r'~ '"~-"""'~~-------- 1 f the current f1 owing through conductor A is turned off, the magnetic field around conductor A collapses, and voltage is again induced in con· ductor B. However, now the current flows thr'ough conductor B in the opposite direction. induced voltage causes current to flow in the opposite direction when the magnetic field is collapsing than it does wt1en the field is bui1ding up. 4~ 2 ,, BASIC ELECTRICITY REV[EW 4. Electromagnetism (continued) Current flowing through a DC circuit does not change unless it is switched on or off. In an AC circuit, however, because the current flow is con- stantly changing direction, changes occur man.Y times per second in the electromagnetic field. Changes in current flow in an AC circuit have the same effect as switching current on or off in a DC circuit: They cause the magnetic field to build up or collapse. 4. 2 Transfm·mers Transformers are AC components that make goad use of the induction process. Different types of equipment require different voltages to operate, and transformers are used to change AC voltages to meet each specific require- ment. Figure 4-2 shows the parts of a typical transformer: two con- ductors, A and 8, coiled around a metal core. The first conductor, labeled A in the figure, is the primary coil. Shaping this conductor into a coil increases its magnetic field. The second conductor, labeled B in the figure, is the secondary coil. This conductor is coiled in order to increase its exposure to the primary's magnetic field. Both coils are usually wound around a metal core, 1~hich concen- trates and directs the magnetic field. Current is sent through the primary side of a transformer. The changing magnetic field that is created around the primary coil induces a voltage in the secondary coil. ~-3 BASIC ELECTRICITY REVIEW 4. Electromagnetism (continued) The purpose of m6st transformers is to step up (increase) or step down (decrease) voltage. There is a direct relationship between the number of turns in each winding and the amount that voltage is changed from the primary to the secondary. For example, If there are more turns in the secondary winding than in the primary winding, the primary's magnetic field will have more conductors to cut across. The induced voltage will, therefore, be greater than the applied voltage. Figure 4-3 shows the way a typical step-up transformer is built. There are more turns in the secondary coil than in the primary coil. The voltage output frcro this and all otht!r transformers is determined by the ratio between the number of turns in the primary coil and the number of turns in the secondary coil. In the transformer represented in Figure 4-3, there are five turns in the primary coi 1 and ten turns in the secondary coi 1. Because there are twice as many coi 1 s on the secondary side as on the primary side, the output va1tage is twice the input voltage, An increase in voltage causes a corresponding decrease in current. The output current in this example is half the input current. When voltage is doubled, current must be halved so that the power (voltage times current) going into the transformer's primary side is equal to the power coming out of the secondary side. 4-4 BASIC ELECTRICITY REVIEW 4. Electromagnetism (continued) Figure 4-4 shows ho~1 a typical step-down transformer is set up. In this transformer, the pl'imary coil has three t·irnes as many turns as the secon- dary coil. This means that the output voltage is one-third as much as the input voltage. Power in must equal power out, so the output current is three times as much as tt1e inrut cun·ent. This tranformer steps down voltage, so it increases current. Questions 4-1. What is electromagnetism? 4-2. True or False. A change in the flow of current through a conductor causes a change in the electromagnetic field surrounding that con- ductor. 4-3. Induction only occurs when a mangPtic field is (a) or (b) BASIC ELECTRICITY REVIEW 4. E 1 ectromagnet ism (cant i nued) 4-4. In (a) circuit, the magnetic field builds up and (an AC, a DC j collapses continually, while in (b) circuit, the magne- (an AC, a DC) tic field builds up and collapses only when current is turned on or off. 4-5. Circle the best answer. The purpose of a transformer Is to increase or decrease a. Voltage b. Resistance d. None of the above 4-6. lndicate the correct reason for coiling the primary and secondary conductors in a typical transfonner. Write the correct number in each blank. a. ---~-· rimary b. ______ econdar y 1. 2. To i ncr·ease the magnetic field of the conductor To increase the exposure of the conductor to the magnetic field tl-7. True or False. The purpose of the metal core in a typical trans- f:)nner is to concentrate and direct the magnetic field. 4-!J. A step-down transformer (a) vo1 tage; a step- (decreases, increases) up transformer (b) voltage. (decreases, increases) 4~9. The ratio between the number of turns in the primary coil and the number of turns in the secondary coil determines the __ _ of a transformer. 4-10. If a transformer has 1200 turns in the primary coil and 120 turns in the secondary coil, the output voltage will be (a) the input voltage; the output current will be (b) the input current. 4-6 BASIC ELECTRICITY REVIEW (continued) 5. Inductance and Inductors OBJECTIVES: • Define self-induction. • Describe the characteristics of inductance. • Describe the parts of a typical inductor and explain what an inductor does. 5.1 Self-Induction As stated in Section 4, induction is the process that produces a voltage in a conductor due to the effect of a changing magnetic field. In the type of induction described in Section 4, a voltage is produced when the lines of force from a changing magnetic field around one conductor cut across another conductor. Ther-e is also another type of induction that takes place. This type is called self-induction, and it occurs within a single conductor. In self-induction, a change in the electromagnetic field around a single conductor induces a voltage in that conductor; the lines of force in the field cut across the conductor itself. Self-induction is present in every current-carrying conductor. It always opposes a change in current in the conductor, so it has the effect of keeping current fr001 building up when it is first turned on and keeping current flowing after it has been turned off. The actual interval of time that elapses before current flow overcomes the effect of self-induction is very small -only a fraction of a second-but the fact that there is a time 5-1 BASIC ELECTRICITY REVIEW 5. Inductance and Inductors (continued) interval is Important. Figure 5-l illustrates the way that current would flow if there were no self-induction. In this graph, current flow reaches maximum value almost instantly. Figure 5-2 illustrates the way that cur- rent actually builds up, because of the effect of self-induction. v/ith self-induction, current flow increases to its maximum value gradually. Graphs showing the effect of self-induction when current is turned off would show a similar relations~tip. Without self.,.,induction, current flow would stop irrrnediately. With self-induction, current flow gradually de- creases over an intel·val of time until it reaches .zero. TfTt1E: 5-( c{~r t:141 ~~~~ '*> 5£Lf· I#OOClioN 5. 2 Inductance 5"-~ t:Lcrz:::trt nav LUfrif S;.L·f-tl'.ltW~'\t.N Inductance is a physical property of all conductors that tends to keep current flow from changing. The amount of inductance present in a con- ductor determines the amount of voltage that is produced by self- induction. 5-2 BASIC ELECTRICITY REVIHJ 5. Inductance and Inductors (continued) The shape of a conductor has a significant effect on how much inductance it has. For example, in the straight conductor pictured in figure 5-3, the lines of force from the electromagnetic field that surround the conductor only cut through the conductor to a limited extent. 5-3 BASIC ELECTRICITY REVIEW 5. Inductance and Inductors (continued) However, as shown in Figure 5-4, with a coiled conductor, the changing magnetic field cuts through the loop where the current originates and through each additional loop as well. Therefore, the amount of inductance in the coiled conductor is far greater than the amount of inductance in the straight conductor. 5-4 BASIC ELECTRICITY REVIEW 5. Inductance and Inductors (continued) It is possible to increase the amount of inductance in a coiled conductor even more by winding the coil around a metal core (Figure 5-S). The core tends to concentrate the magnetic field even further, and thus increase the effect of inductance. Because 1 nduc tance is a phys i ca 1 property that is present in a 11 con- ductors, it affects both OC circuits and AC circuits. The presence of inductance in a DC cil·cuit can cause problems when current is switched off. 5-5 BASIC ELECTRICITY REVIEW 5. Inductance and Inductors (continued) Figure s~6 shows an open switch in a DC circuit. An open switch indicates that current flow has been shut off. But due to the inductance present in the circuit, current tends to continue flowing. The result shown in the figure is arcing. Arcing is cw·rent flow through air across an open switch. Arcing is undesirable, and it can damage a switch. DC circuits are usually designed to minimize inductance so that this doesn't happen. In AC circuits, however, the effects of inductance are sometimes used to good advantage. Some AC circuits are intentionally designed to increase the amount of inductance they contain. 5-6 !0"'· ·• oio"··r . ' . .,., BASIC ELECTRICITY REVIEW 5. Inductance and Inductors (continued) 5.3 Inductors Inductors (Figure 5-7) are components specifically designed to increase the amount of inductance in AC circuits. Two common types of inductors are iron core inductors and air core inductors. All inductors are put together in about the same way. A typical inductor is composed of a conductor wound around a core. The conductor is usually made of solid copper wire coated with insulation; the core is usually made of either a magnetic material or an insulating material. When the core is mad e of magnetic material, its purpose is to strengthen the electro- magnetic field surrounding the conductor. When the core is made of insula- ting material, its purpose is to support the coil. When heavy wire is used for the conductor, a core is not necessary for support. An inductor that does not have a core is usually called an air core inductor. Inductors are often called chokes or coils . 5-7 BASIC ELECTRICITY REVIEW 5. Inductance and Inductors (continued) Inductors are often marked with a color code that is similar to the one used to mark resistors. Information about color codes is included in Appendix A to this text. When numbers are used to indicate the va'lue of an inductor, the numbers refer to units of incluctance, which are Henrys. One method of testing an inductor is to measure its rt;sistance with an ohmmeter. lf the inductor is damaged, its resistance reading w11l be high. A high resistance reading through an inductor-indicates that there is an open circuit s~ewhere in the inductor. An open will keep an inductor from functioning properly. Questions 5-L True or False. It is possible for voltage to be induced in a single conductor. 5-2. True or False. Self*induced voltage always opposes a change in current. 5-3. Inductance is a that is present in all conductors. 5~4. True or False. It is possible to increase the amount of inductance in a conductor by winding the conductor around a core made of mag- netic material. 5-5. Name two parts of a typical inductor. a. b. 5-8 BASIC ELECTRICITY REVIEW (continued) 6. Capacitance and Capacitors OBJECTIVES: t Define capacitance. • Describe a typical capacitor and explain how a capacitor stores energy. • Explain the hazards associated with capacitors . 6.1 Capacitance Capacitance is the ability to store electrical energy. Capacitance is a physical property of every electrical circuit. There is some capacitance present whenever any two conductors are located close together. 6.2 Capacitors Capacitors are used to control and increase the amount of capacitance in electrical circuits. Figure 6-1 shows the parts of a typical capacitor. There are two plates separated by an insulating material. etJND~n~ PlJl.\(~;; V4\;>\C fht'l•> r:f fl. \_1AP~D I(,-.(<, G-l ) \ t BASIC ELECTRICITY REVIEW 6. Capacitance and Capacitors (continued) A capacitor is charged by connecting it to a voltage source. The voltage source forces electrons to flow onto one plate, giving it a negative charge. A negative charge repels electrons. The negative charge on the first plate forces electrons to move away from the second plate, leaving the second plate with a positive charge (Figure 6-2). An electrostatic field builds up between the capacitor plates because of their positive and negative charges. An electrostatic field is the space that electrons would move through if a conducting path were avail able. The electrostatic field would cause current to flow if there were a conducting path between the plates, but no current path 1s provided. 1 t is the presence of the electrostatic field that allows the capacitor to store energy, and it is in the electrostatic f~eld that the energy is stored . The insulating material between the cap@citor plates blocks the flow of electrons from one plate to another. In order to discharge a capacitor, a conducting path must be provided between the plates. Opening the circuit 6 -2 .. , t! ... j BASIC ELECTRICITY REVIEW 6. Capacitance and Capacitors (continued) by removing the voltage source from the capacitor will not discharge it. It is necessary to connect the plates by providing a path between them in order to discharge the energy stored in the electrostatic field . . As stated earlier, capacitance is a physical property of every electrical circuit. It is a measure of a circuit's ability to store energy 1n an electrostatic field. The capacitance of a capacitor is determined by three factors: (1) the surface area of the conducting plates; (2) the distance between the plates; and (3) the insulating properties of the material that separates the plates. 6 . 3 TyPes of Capacitors The capacitors shown in this text are typical examples of the wide range of capacitors in use today. The capacitance of a capacitor is measured in units called Farads. The value of a capacitor may be printed right on it, or the value may be indicated by means of a color code. Information on color codes is included in Appendix A to th1s text. EachofthecapacitorsshowninFigure 6-3 is made up of two flat plates separated by insulating material. I ... . ,, ,, 7'0"-0-V/ vz, !"ll'l Dt~:. u.ft,'\t~\Tbr.S 6-3 BASIC ELECTRICITY REVIEW 6. Capacitance and Capacitors (continued) The capacitor shown in Figure 6-4 is enclosed in a metal case. This capacitor is made up of a series of flat plates. A special kind of oil provides the insulation around the plates. It is capable of storing more energy than the capacitor shown in Figure 6-3. Large high~voltage capaci- tors of this type are sometimes found in industrial plants and electrica l switchyards. The capacitor shown in Figure 6-5 is an electrolytic capacitor. It con- tains a chemical paste and a metal plate. A chE1llical reaction takes place between the paste and the plate. Using this method of construction, it is possible to build a capacitor with the ability to store a great deal of energy. The polarity of electrolytic capacitors is always marked plainly on their surface, because they must be connected with their positive side on the positive side of the circuit and their negative side on the negative side of the circuit. If an electrolytic capacitor is not connected this way, the chemical reaction within the capacitor could ca.use it to burn or explode . 6-4 BASIC ELECTRICITY REVIEW 6. Capac i tance and Capac i tors (continued) Figure 6-6 shows a variable capacitor·. It contains two sets of plates instead of two single plates. All of the plates in each set are connected together. In order to change the capacitance of the component, an adjust- ment is made to each set of plates. Air is the insulating material used in this type of capacitor. {p .{[; VA~I A0Lf-C~(..liO It 6-5 BASIC ELECTRICITY REVIEW 6. Capacitance and Capacitors (continued) 6.4 Hazards of Capacitors All capacitors, and all systems that have a significant amount of capaci- tance, can be dangerous. Unexpected capacitive discharge can cause injury to personnel and damage to equipment. In order to prevent accidents due to unexpected capacitive discharge, the following steps should be taken: (1) always be aware that the danger of capacitive discharge exists; (2) check to be sure that a capacitor or system has been discharged before working with it (a voltmeter can be us.ed to detet'mine whether or not the capacitor is charged); and (3) if necessary, discharge the capacitor or system. Discharging is accomplished by connecting the charged conductors together, grounding them, and allowing the charge between them to equalize. Proper safety precautions must always be observed, because discharging, itself, can be hazardous. An ohniTieter can be used to check whether or not a capacitor is bad. A capacitor should not show a complete current path-if it does, it will not function properly. The ohmneter should show infinite resistance through the capacitor, indicating that there is not a complete current path. Questions 6-l. Wt1at is capacitance? 6-2. True or False. Capacitance is a physical property that is only found in circuit~ containing alternating current. 6-3. True or false. Capacitors are components that store up electric char·ges. 6-4. The plates in a capacitor are separated by an material. ------ 6-6 BASIC ELECTRICITY REVIEW 6. Capac Hance and Capacitors (continued) 6-5. True or False. When a capacitor is discharged, the energy stored in the electrostatic field is released. 6-6. True or False. A capacitor can be discharged by removing it from a voltage source. 6-7. Name the three factors that determine the capacitance of a capac- itor: a. b. c. 6-7 BASIC ELECTRICITY REVIEW (continued} APPENDIX A COLOR CODES Ill. Resistors The standard resistor color code adopted by the Electronic Industries Association (EIA) uses colored bands to indicate both the nominal value and the tolerance of a resistor. The arrangement of the bands is shown in Figure A-1. ~;.ts1STc~·, (\j:: 1 ~~ c, ~'\ ~ The meaning of each band can be found in the following table: FIRST SECOND MULTIPL Y!NG COLOR DIGIT DIGIT V/\LUE TOLERANCE Gl ack 0 0 1 Grown 1 10 Red 2 2 100 Orange 3 3 1' 000 Yell ow 4 4 10,000 Green 5 5 100,000 Blue 6 6 1 '000' 000 Violet 7 7 10,000,000 Gray 0 ') 8 100,000,000 I~ hi te 9 9 1,000,000,000 Gold 0.1 + 5% Silver 0.01 + 10% -- No Color + 20% App, A-1 BASIC ELECTRICITY REVIEW Appendix A: Color Codes (continued) The multiplying value is the number by which the first two digits must be multiplied to obtain the actual value of the resistor. If the third color band is orange, for example, the two-digit number indicated by the first two color bands is multiplied by 1000. The tolerance is the manufacturer's tolerance. If the fourth color band is · gold, f.or example, the actual value of the resistor is within five percent of its indicated value. If there is no fourth color band, the tolerance is + 20%. Example A-1: Find the value of the resistor represented in Figure A-2. --~~-- The first color band is brown, so the first digit of the resistor value is 1. The second band is blue, so the second digit is 6. Because the third band is red. the first two digits must be multiplied by 100: 16 x 100 : 1600 ohms The value of the resistor is 1600 ohms. Because there is no fourth band, the tolerance is + 20 %. App, A-2 BAS lC ELECTRICITY REV lEW Appendix A: Color :odes (continued) A2. The color· codes used for capacitor identification at·e similar to the one used for resistors, but capacitor identification is not well standardized. There are several different color code systems in use. Usually, it is necessary to obtain tilE color· code for e~ particular· capacitor fl'orn its man1;f actLwe!·. Dne tyoical color code system is described het'~. The arrangement of colored bands ·fw this systerr1 is shovm in Figure A-3 . C /11)1\GrT•~ c~~UrltJ. . , t\ ( t:~ lt,..; The meaning of each band can tie found in the following table: FIRST SECOND MULTIPLYING COLOR DIGIT DIGfT VALUE TOLERANCE G 1 ack 0 0 1 + 20% Brown 10 + 1% Red 2 2 lOC + 2% Orange 3 3 1,000 + 3% Ye 11 ow i.j 4 10,000 + 4% G"een " ,l 5 100' 000 + 5% B 1 ve 6 6 l '000, 000 + 6% Violet 7 7 10,000,000 + 7% Gray 8 8 1 00 '000 ' 000 + 8% ~~hi te 9 9 1,000,000,000 + 9% ~ Gold 0.1 + 5% ~ S j 1 ver 0.01 + 1 ():'~ App. /\-3 VOLTAGE RATING lOOv ZOOv 300v IJOOv 500v 600v 700v 800v 900v lOOOv 2D00v BASIC ELECTRICITY REVIEW Appendix A: Color Codes (continued) The value of a capacitor as determined by this system ·is in picofarads. The farad is the basic unit of capacitance, but one farad is a ve:ry large amount of capacitance. The more conrnonly used units are microfarads ( l.l F) and picofarads (p f). One microfarad is equal to one millionth of a farad. One picofarad is equal to one millionth of a microfarad. Example A-2: Find the value of the capacitor represented in Figure A~4. The first band is orange, so the first digit is 3. The second band is green, so the second digit is 5. The third band is blue, so the first two digits must be multiplied by 1,000,000: 35 X 1,000,000 ; 35,000,000 The capacitance of the capacitor is, therefore, 35,000,000 picofarads, which is the same as 35 microfarads. The fourth band on this capacitor is black, indicating that the manu- facturer's tolerance is! 20%. The fifth band is yellow, which means that the capacitor is rated for 500 volts. A3. Inductors As with capacitors, the colQr codes used for inductor identification are not well standardized. The particular inductor manufactur~r's color code must be used in order to get the correct inductance value. App. ,n,_ 4 t.', BASIC ELECTRICITY REVIEW Appendix A: Color Codes (continued) One typical color code system is described here. The arrangement of colored bands for this systen is shown in Figure A-5. 11-lf~D (,.fTuJ<. rM.k..-nhVIM~ \fAt tfle The meaning of each band can be found in the following table: FIRST COLOR DIGIT 81 ack 0 Bro·..,n 1 Red 2 Orange 3 Ye 1l ow 4 Green 5 B 1 ue 6 Violet 7 Gray 8 White 9 Gold S i I ver No Color SECOND DIGIT 0 1 2 3 4 5 6 7 8 9 THIRD DIGIT 0 1 2 3 4 5 6 7 8 9 MULTIPLYING VALUE 1 10 100 1,000 10,000 TOLERANCE + 5% + 10%. + 20% The basic unit of inductance is tt1e henry. A henry is too large a unit for most practical applications. The unit of inductance that is more cornmon·ly used is the microhem·y ( p.H), which ·is equol to one mil1 ionth of a henry. Tht; value of inductance dctennined by this system is in microhenrys. App. f\-5 BASIC ELECTRICITY REVIEW Appendix A: Color Codes (continued) The third band in this system may be either a third digit or a multiplier. lt is a third digit when the inductance is below 10.0 11 11, and it is a multiplier when the inductance is 10.0 JlH or above. The first two bands indicate if the inductance is below 10.0 t.L H. For any value below 10.0 ~( H, either the first or second band will be gold, indicating the position of the decimal point. If neither the first or second band is gold, the value is above 10.0 ll H. Example A-3: Ffnd the value of the inductor re[!resented in Figure A-6. The first band is gray, so the first cligit iS 8. The second band is yellow, so the second digit is 4. Neither the first or second band. is gold, so the value is 10.0 ~t 11 or above, and the third band is a multiplier. The third band is brown, so the multiplier is 10. The inductance is, therefore, 840 11 H. The fourth band is gold, indicating that the manufacturer's tolerance is + 5%. The tolerance band on inductors is often a double-width band in orGer to differentiate it from the other bands. App. A-6 . MAINTENANCE TRAINING AC FUNDAMENTALS REVIEW . VOt..TA:n: ISSUED TO:. _____________ ·-----·-----··---- DATE: ---------~ CHECKED BY: __ Section L 1.1 L2 TABLE OF CONTENTS Title Alternating_ Current Current Flow and Po 1 ar i ty .... .-' ................ . Sine Waves ................................. ~ .. ~, ... . 1-l 1 l 1-5 1.3 Peak Values, Peak-to-Peak Values, and Effective 2. 2.1 2.2 2.3 3. 3.1 3.2 4. 4.1 4.2 4.3 <1.4 5. 5.1 5.2 5.2.1 5.2.2 Values • • • . • • • • • • • . . . • • • • . • . • . • . • . • . . . . . . . . . . • . • . 1-8 1 nductance ••••••••••••••.•.•••••.•.••......••... Inductance and Inductive Reactance .•....•.•.•... Factors That Affect Inductive Reactance .•.•.•... Effects of Inductance on Current and Voltage .••. Capacitance .............................. , . , ..... " .. , ....... .. Capacitor-; •.•••.••...••.•.•.•.•••.•.•••.•.•.••.• Effects of Capacitance on Current and Voltage ..• AC Power •.•••••••••••••••••.•.••.••••••••••••••• True Power ..•.•....•.•..•...........•..........• Reactive Power Apparent Power ••••.•••••..••.•.•.••.•.•.•.•....• Power Factor Single-Phase and Three·Phase Systems ••....•...•. Single-Phase Systems •••.••...........••.•..•...• Three-Phase Systems ........•.•........•.•••..... Delta Connections ....••..•...•....•............. W.ye Connections .•....•..•..................•.••• 2-1 2-1 2-3 2-5 3-1 3-2 J-4 4-1 4-1 4·2 4-5 4-6 5-1 5-2 5-3 5-4 5·5 1. Alternating Current (continued: Figure l-2 :;'lows a simplified AC genera:or. This ger:erator produces volt- c:ge by mean:; of incuctior.. The tnree requh·emer,t; for in::Jucins voltage are: o c()ndJcto,-, a 11agnctic field, and relative mot~cn. lr. t•JiS gcr.- erator, a loop of wire is the condL.ctor, and the rn.1gru:>tic field is prov ded b_v a permune~lt vis~b;e in the figure.) rotated the (The ncrth .;;nd srmtn po 1 es of L~~ magnet cr.:: The relat1ve motion occurs wh~n the conauctor ts c fielc. Th~ s1mplified generator has two riior·e corrponents: 'slip rings and brusne>.. The !>lip rings are attached to the ends of the co:Jd-cto•·, they s i ide against the brushes as the cuncluctur rntntes. Current produced jy the generated vol cau 1 d f l:;w t11rough the crushes and thrauyh d ~ircuit connected to tne generator. The ffiagnetic fielc, indicated by the ~lue lines in Figure 1-2, is made up :Jf numoer of lines of fL;x. (For simolicity, the lines are sl1own as s tr c i gr: 1 i nes. Act;.. a 11 y, they are curve::1. ) Wnen the conductor Lw·ns, eac'l ha;f cf the lcop cuts ~hrough the magnetic lines of f7ux, fitst in one directior ana then in the opposite direction. Because the conduclor moves 1r1 a circular pat~ern, its rotation can be demonstrated by using the 360 (Jegrees tnat make -'P i.l circle. This moveT:ent is i histrated 1n rigL..re :-3, 'o'lhich shows an r.nd vie\\· of the cor.ductor, without the slip rings or btu >hes. For eJs e cf <::<:pI ana~ ion, ttle ti'IO ends of the conductor' r;ave been labeled~ .;~nrl Y. 1-.5 P..C FUNDA."lENTALS REVlEW l. Alternating Current (continued) At zero degrees, the ends of the con- ductor are not cutting across any of [R[ the lines of flux. Since there is no ~ relative motion between the conductor ana the magnetic field, no voltage is i nducec. As the conductor starts to rotate, the X cr. a Qf the conductor begins to cut the magnetic field in a downwarc direction, while theY end of the con- ductor cuts the magnetic field in an upward direction. Now. voltage is be- ing induced. As the conductor moves to·n'ard 90°, more and more flux 1 i nes are cut, so the induced volt age in- creases. Maximum voltage is 1nduced at the instant that the conductor reaches the 90-aegree point. As rotation cont1nues towards 180 degrees, the conductor cuts fewer and fewer flux 1 i nes, so the induced voltage decreases. When the con- ductor reacnes 180 degrees, the con- ductor is cutting through no lines of flux, so no voltage is induced. 1-4 X 0 0 )s y AC Fdl01~'1cf\TALS R:::Vlt.w l. Alternating Current (conl1nuec) At 180°, the polarity changes. The X end of tile conductor starts cutting the magnetic fleld In an upwarG direc- tion, while the Y end cuts the field ir. a downward direct10n. From 180 to 270 degrees, t ne conductor once agd in cuts through more and more 1 i r.es of flux. At the instant that the con- duct or reaches 270 degrees, it is again cutting the :naximum number of flJx lin~s, so malim~m voltage is in- duced. As ro~ation continues fro~ 270 degree'-to 350 degrees, voltage be- gins decreasing, because the con- ductor is cutting through fewer and fewer lines of flux. When the con- ductor completes its rotation. at 360°. no vu l is induced, because no flux lines are oeing cut. 1.2 Sine Waves X CE: (~) )~_ y The direction in which a conouctor cuts a :nagnetic fiela, or the direction in wnicn a magnetic field cuts a conductor, determines the polarity of the voltage that is induced. An easy method of showing how the poldrity cnanges is to use a graph. AC FUNDAMENTALS REVIEW l. Alternating Current (continued) Figure 1-4 is a graph that represents the voltage induced as the conductor in Figure 1-3 makes a complete rotation through the magnetic field. n vertical line of the graph represents the magnitude of the induted voltage. Voltage that i5 above the horizontal line is positive, and voltage that is below the horizontal line is negative. Voltage that is on the horizontal line is neither positive nor negative -it is zero. (On this graph. the horizontal line ahn represents the time that elapses as the voltage changes.) + At zero oegrees, the conouctor is not cutting through the magnet1c field, so no voltage is induced. As the conductor rotates toward 90 degrees, more and more lines of flux are cut, so voltage increases. At 90 degrees, the induced voltage reaches its maximum positive value. From 90 degrees to 180 degrees, voltage decreases, because the conductor cuts acros~ fewer and fewer lines of f1ux. At 180 degrees, no flux lines are being cut, so no voltage is induced. At this point, the conductor starts to cut acro:>s the flux lines in the opposite direction. From 180 degrees to 270 de9rees, 110 ltage increases in th~ negative direction. At 270 deQrees, it reaches its maximum negative value. From 270 degrees to 360 degrees, voltage de- ere ases again. At 360 .degrees, vo lLage is again 20ro. because the con- ductor is not c~tting across any flux lines. 1-6 AC FJ(;Otl,."'E~nr,_s REVI£,. 1. Alternating Current (contjnued) Tne type of graph shol'ln in Figure l-4 is called a sin~..soidal curve, a sine cur'IE:, or a s\ne wave. A sine wa·'le has no shar;:> benus :)r straight !JOr· tions; it 1s just a smooth rise and fil:l. Sine waves are often '.Jsed to r;lo: electrical quantities. If the sir.lpiif1ed generawr shown in Figun: l-2 were pan of a ccmplete circui:, the inducec voltage would cause current to Cow. In r)~Jre 1-5, a currtnt sine wave has oeen added to the vcltage sine Wdve shown in Figure l-11. lhe current sine '"ave represents current flm>~ ttJrouyh tne complete c1rcuit. + ';lnen the conductor is at zero oegrees, no vo 1 tage is induced, sc. 110 current can flow. As the conductor begins to rotate, voltage and current increase. Both voltage and curren~ reach their maximum va )ues at 90 degrees. As rotation continues, botn voltage and current decrease. At lSO degrees, no voitage is induced, so no current flo~s. from 180 degrees to 27C degrees, voltage ana current increase in the negative direction, reaching tneir maximum negathe values at 270 degrees. Finally, as the conductor· moves from 270 to 360 deyrees, vo I tage ami current oecr ease. 1\t 360 degree~, both voltage ano current are again zero. -7 AC FUNDAMENTALS REVIE'I'i 1. Alternating Current (continued) In this example, each time the conductor rotates a full 360 degrees, it completes a cycle. In a typical AC power system, 60 cycles are completed every second. The number cf cycles completed each second by a given AC voltage is called frequency. Frequency is measured in units called hertz. Sixty cycles per second can. therefore, be referred to as 60 hertz, or 60 Hz. 1.3 Peak Values, ?eak-Ta-Peax Values, and Effective Values The amount of voltage or current at the maximum positive or negative point on a s1ne wave is called the peak value of the vo1tage or current. Peak values occur twice in each cycle: once positive and once negative. The amount of voltage or current repres~nted by the d1~tance between the posi- tive peak and the negative peak is called the peak·to-peak value. Peak values and peak-to-peak values are not commonly used for AC current or voltage except when designing AC equipment. {For example, the insulating rating on equipment is based on peak voltage.) Most often, effective values are used. The reason for using eff~ctive values instead of peak v~lues 1s that alternating current does not maintain a constant value. It does not build up to a peak and then stay there, like direct current does. A peak. AC value is not equivalent to a DC value with the same numbers: 120 volts peak AC voltage is not the same as 120 volts OC. When scientists conducted tests to find the exact relationship between peak AC values and DC values, they discovered that one ~pere. peak value, of alternating cur- rent produces the same heating effect as .707 amperes of direct current. This relationship, whlch applies to both current and vo1tage (because voltage produces current) is the basis for effective values. Effective AC values are equal to peak AC values mu)tip1ied by .707. Effective values for AC are often called RMS values. RMS stands for root- mean-square, which refers to th~ mathematical formula used to determine effective values. The formula itself is not important here. What is important is to understand th•t RMS values are used to rate operating voltages on almost all AC equipment. Most meters read RMS values, too. Unless the data plate on a meter or piece of equipment indicates otherwise, all AC values are RMS (effective) values. 1-8 i\C ruNDAI1ENTALS REVIEI'I l. Alternating c~rrent (continued) In surrrnary, peak AC va1ues and peak-to-peak AC values are relatea as follnws: PeaK-lu-peak = 2 x peak Anc RMS values are related to peak values like this: RMS Peak x .707 0 ues t ions l-1. The of an AC power source changes periodica\1y. 1-2. List the three requirements for inducing a voltage. a. b. c. 1-3. Circle the correct answer. When a conductor rot at 1 ng in a magnetic field is cu tl i ng through the maximum nu~oer of flux lines, a. The conductor stops moving b. No voltage is induced c. Maximum voltage is ind~ced d. None of the above 14. True or False, When il sine wave is used to represent voltag€, voltage below the horizontal line is negative. 1-5. The num~er of cycles completed each second oy a given AC voltage is cafled (a) and is measured in (b) 1-6. The letters used to express effective AC values are-~---- 1-9 AC FUNDi\MENT.I\LS R£VI Eh' \continued j 2. r nductance OBJECTIVES: • Define inductance ana inductive reactance. • Explai~ how inductive reactance limits current flow. • Differentiate between in~phase ana out-of-phase cur- rents and voltages. Ohm's Law states that current is equal to voltage divided by resistance. In DC circuits, Oh~'s Law holds true for all applications, because the only two factors :hat affect DC current are :esistance and vo1tage. AC current. however, is affected by additional factors, ·t~nich must be taken into ac- count. Like DC o .. wrent, AC current is affected by voltage and resistance, but AC current is also affected by inductance and capacitance. InductancE is covered in this section; capacitance is covered in Section 3. 2.i Inductance and Inductive Reactance Inductance is a physical property of all AC circuit:> that opposes any change in current flow. It is measured in units called henrys. The symool for inductance is a capita1 L. Inductive reactance is the measure of the opposition to current flow that is created by inductance. Stnce inductive reactance, 1ike resistance, limits current flow, it is measured in ohms. The common symbol for inducti\le redctance is XL. The 't'alue of inductive reactan::e, in ohms. can be calculated by using the following fom•u1a: where: " is f is L. is 2~ l ii\., •U>l,..lr)liL.!t;r't._.,. ,,..._~..,.._,, 2. ln<Juctance ('continued) To understana ho..: 1nduct1ve reactance limits c.:.trrent flow, 1t is first necessary to understand a process called self-induction. Current flow is dCtua~ly limited by an induced voltage that opooses the appl~ea voltage. Tnis induced voltage is callea counter voltage or, rrore con111cnly, c:Jc.mtet· elr.ctrornotlv!:' fo•·ce (CEMF). Counter electromotive force lS caused seJ:'~induct1on, whicn is tr1e induction of voltage in (l conductor ;\C CJrrent flowing through tnat same conauctor. When voltage 1s applied to a conductor, current starts to flow through the conductor. The current flow causes a magnetic field to bui lc up around tne conductor, as shown in Figure 2-1. The magnetic field continues to expand uut'l'iard from the center of the conductor e1nti l tne current that is pr-o- ducing it reaches its peak value. ~h~le tne magnetic field ts building up, there is relative motion between it and the conductor, because the field itself is moving. And, whenever there is a conductor, a magnetic field, and relative motion, voltage is induced. In this case, as the magnetic field builds up, its motion induces a voltage in the conductor. Since the current-carrying conductor is in- cueing a voltage in itself, the process is called self-induction. The inducea vcltage, which is opposlte in polarity to the applied voltage, is coJnter electromotive force. ·3ecause the C!)F opposes the applied volt- age, it lim1ts current. 2-2 fl'-' I \o.h1Vf"V'll..l\ I r,i,.,J £) t, f • i.,. ff 2. lnductance (continued) After the current flowing througn the conductor reaches its pea~ value, it decreases until it reaches zero. The decreas!ng current causes the mag- netic field tc collapse. The motlcn of the magne~ic field co11apsing is opposite to the motion of the field building up, Since the motion is opposite, the self-induction is also opposite. The voltage that is induced ir-the conductor now has the same polari:y as tne applied voltage. When the magnetic field has collapsea completely, there is no motion ana, therefore, no ·self-induction. Then, as the current again increases to- wa:ds its peak value, this time ~ith the opposite polarity, the magnetic field again builds up. Whenever t:here is a change in the curre!'lt, the magne:ic field also changes. The voltage that is induced in the conductor by the changing magnetic field is always in such a direction as to oppose the current change. So, if current is trying to increase, the inouced voltage opposes the applied voltage; lf current is trying to decrease, the induced voltage aids tne applied voltage. 2.2 Factor~ That Affect Inductive Reactance There are several factors that affect the amount of inductive reactance - the amount that current flow is limitea by :nductance-ir a circ .. Jlt. For example, inductive reactance can be increased by coiling a conductor. It can be increased even more by placing a metal core inside the coil. The basis behind both of these factors is that the number of lines of flux that cut a conductor affects the amount of inductive rea~tance. Anythi~g that increases the number of magnetic lines of flux cutt1ng a conouctor in· creases the inductive reactance. Likew1se, anything that decreases the number of magnetic lines of flux cutting a conductor decreases the indue~ tive reactance. 2-3 .U.C fU/1DA'<iENT!l.LS ?.EV 1£1-i 2. Inductance (continue~) A contluctor that is wound into a coil provides more induct1ve reactance that a straight conductor. A straighL conductor is cut only once by its magnetic field when the magnetic fie\o changes. in a coiled conductor, as sno·l'l'n in Figure Z-2, the magnetic fiela frOOJ each turn cuts across the other turns. The more turns there are in the coil, the nigner the lnduc- tive reactance will be. 2-4 AC FUNQMENTALS. REVIEw· 2. Inductance (continued) The inductive reactance that a coil provides can be further increased by placing a metal core inside the coil, as sho.,.,·n in Figure 2-3. -rhe magnet, field produced by the coil is concentrated and directed ny the metal core. so more lines of flux cut across the conductor as current changes. Since inducttve reactance limits current, a change in inductive reaci:ance also means a change in current. Increasing the inductive reactance de- creases the current, and decreasing the inductive reactance 1ncreases the current. 2.3 Effects of Inauctance on Current and Voltage The current ana voltage sine waves shown in Section 1 were associated with a circuit that had only resistance as a current-1imiting factor. Any inductance in tne circuit was considered to be so small that it was in- significant. Such a circuit is ca11ed a purely resistive circuit. The term "purely resistive" means that resistance is the only factor that lim1ts current flow. 2-5 K\.. r Ulli..-/'\i'lL·11 i''H .. :J !:'IC V 1 C.W 2. IndJctance (contin~ed) .n purely resistive circuits, when voltage increases, current also in- creases . S i nee vo 1 tage ana current stay toget.r1er. a l ·t~ays i ncr easing or Gecreasing in the same direction at the ~arre ti~e. they are said to oe in phast:. Fig1Jre 2-4 s.hows in-phase voltage and current sine waves for a purely resistive circuit. + 2~ 6 AC FUNDAMENTALS REV IE~ 2. Inductance (continued} Figure 2-5 shows sine ~aves for voltage and current in a purely inducti~e circuit. A purely inductive circuit is a circuit that nas only inductive reactance as a current-limiting factor. Actually, there is no circuit that is purely inductive, because there is ah!'ays scxne resistance 1n a circuit. However, the idea of a purely inductive circuit is helpful in understanding the effects of inductance on the relationship between voltage and current. + In a purely inductive circuit, when voltage starts to increase. current does not change right away. The counter EMF keeps current from increasing immediately. Therefore, the increase in current takes place later than the increase in voltage. When voltage starts to decrease, the induced voltage opposes a decrease in current. Therefore, the decrease in current takes place later than the decr-ease in voltage. Because the changes in current a 1 ways_ take p 1 ace later than tne changes in voltage, it can be said that current lags behind voltage by 90 degrees during the entire cycle. 2-7 AC FU.'JlJr'\l·IE~TtiLS REV I E~oi 2. lnductance {continued) whenever voltage and current incredse ar.d decrease at dlffere11t t111es, they are sa1d to oe out of phase. I:~ a purely inductiv£: c'ircliit, inouc- ta1ce ca~ses voltage and current to_ De out of phase.· ~est ions 2-l. The phys1eal proper-:::y of all F1C circJits that opposes any ct1ange H: is called inauctance, 2-2. -------~------ i5 the measure a~ the oppos t1on to current flow that is created by inouctonce. 2-3. Circle the correct answer. When current flo;•;ing through a conductor is 1ncreasing, a. The magnetic field around the conductor is building LiP b. The magnet1c field around the conductor is co;laps1ng c. No voltage is induced d. There is no magnetic field around tne conouctor 2-4. True or False. When CEMF opposes the applied voltage in an AC circwit. it has the effect of increasing current. 2-5. List :wo ways t3 increase in~uctive reactance in an AC circuit. a. ---------~--~-----~ b. 2-6. In a purely inductive circu1t, current-limiting factor. ;-, tht: only 2 ' -I. Whenever voltage and :::urrent increase or decrease at diiferem: times, they .are said to be _____ _ 2-c tiC FUNDIIP1ENTALS REVIE\ol (continued) 3. ~~pacitance OBJECTIVES: 1 Define capacitance and capacitive reactance. 1 Name the basic components of a capacitQr. 1 Explcin the effects of capacitance on current and volt- age. Capacitance is a physical property of all AC circuit5 that opposes a change in voltdge. Capucitance is measurea in units called farads. The symbol for capacitance is a capital C. Capacitiv€ reactance is the measure of the opposition to current flow tnat is created by capacitance. Capacitance and capacitive reactance are related in the same way that inductance and induc- tive reactance are related. Capacitive reactance, like inductive re- actance, is measured in ohms. The comon symbol for capacitive reactance is Xc· The value of capacitive reactance. 1n ohms, ~an be calculated by using tne following formula: wnere: 1 2.trfC " is the constant 3.14 f is the frequency, in hertz C is the capacitance, in farads The effects of capacitance, like the effects of inductance, cause current and voltage to be out of phase. However, as will be explained in this section, the effects of capacitance are not the same as the effects of inductance. In fact, capacitance is often added to AC circuits to counter the effects of inductance. For example, when the inductance in a circuit would limit current flow more ttlan a desirable amount, additiona'l cap- acitance can be added to that circ~.;it to bring currer1t flow up to the level that is needed. The aevice useG to do this is called a capacitor. 3-1 AC FUNDAMENTALS REV!E~ 3. Capc.citance (c:Jntin..:ed; 3.1 Capacitors Capacitors are devices that store er:crsy. A sim?lified capaci~cr 1s s.'"lovm in Figure 3-l. It nas three main cmponents: two plates and an insulator, w:'l:cn is called u. cielectric. The purpose of t.r.e aielectr1c is co keep electrons from flm'iing from one plate to the ot.r1er. The dielectric can be made of any gocd ins~lating mater~al, including air. In fact, air acts as a dialectric whenever two conductors are side-by-side for any significant distance. The two conductors act like capacitc~ plates. 'J ") ~~-L AC FUNDAMENTALS REVIE~ 3. Capacitance (continued) Before a capacitor can store energy, it has to have energy s~pplied to it. The process of supplying energy to a capacitor is called chargfng. Charg- ing . a capacitor requires connecting it to a power source, as shown in Figure 3-2: When the power source is turned on and the switch is closed, electrons flow from the power source to one of the capacitor's plates. This plate thus has an excess of electrons, so it becomes negatively charged. The electrons stay on the negative plate, because the dielectric keeps them from getting to the other plate. Since like charges repel each other, the negatively charged electrons on the first plate~force electrons away from t~e second plate. Therefore, the second plate becomes positively charged. The electrons that are forced away from the positive pla:e flow back to the power source. J-3 2 AC FUNDMENTALS REVIEw 3. Capacitance (continued) Ttre flow of electrons from the power source to the negatively charged plate of the capacitor, and the flow of electrons from the positively charged plate of the capac1tor back to the power source continues until the peak voltage i5 reached. When the peak voltage is reached, the negative plate has gained a certain number of electrons, and the positive plate has lost the Sillfle number of electrons. For any giYen voltage, the specific number of electrons that the negative p1ate can hold is cal1ed the capacity of the capacitor, or simply, the capacitance. Know·ing the capacity of a ca.pa.citor is important. if too much voltage is supplied to a capacitor, two many electrons will be forced onto the negative plate. As a result, the dielectric could break down. lf the dielectric breaks down, current can flow through the capacitor from one p1ate to the other. ln most cases, current flowing through a capac1tor will destroy the capacitor. 3.2 Effects of Capacitance on Current and Voltage '..ihen a capacitor is being charged, a difference in potential develops across it. Each electron that is added to the negative plate makes that plate more negative. and each electron that leaves the positive plate makes that plate more positive. Since a difference in potential is voltage, it can be said that voltage bui1ds up across a capacitor as it is charged. The p9larity of this voltage is such that it opposes the source voltage. As the capacitor continues to be charged, the vo1tage across the capacitor increases until it is equal to the source voltage. At this po1nt, tne capacitor is fully charged. Since the source voltage and the voltage across the capacitor are equal, but opposite in polarity, they have tne effect of canceling each other out, and current stops flowing. 3-4 AC FUNO/lNL11T ALS REV lEW 3. Capacitance (continued) When the source voltage passes its peak, the capacitor starts to dischar·ge. Dischargjng is the reverse of charging: electrons flow onto the positively charged plate ana electrons leave the negatively charged plate. Current now flows in the opposite direction. When the source voltage reaches zero, current flow is maximum ir. the opposite direction. After the source voltage reaches zero, it again begins to ncrease toward its peak value, but with the opposite polarity. The capacitor is again being charged, but in the opposite direction. When the source voltage reaches it5 peak va1ue, the opposing voltage is at its peaK value. At this point, the capacitor is completely charged in the opposite direction; the source voltage and the opposing voltage have the effect of canceling each other out, and current flow is again zero. After the source voltage passes its peak, the capacitor again starts to discharge. When the source voltage reaches zero again, current flow 1s maximum in the opposite direction. The s1ne waves shown in Figure 3-3 indicate the relationship between the source voltage and the current that is producec during a full AC cycle in a purely capacitive circuit. At the beginning of the cycle, as the source vo1tage ri!:.es frorrt zerol current is at 1ts peak positive value. By the time the source voltage reaches its peak positive value, the opposing voltage has built up to the s~~e value {but opposite polarity), so current is zero. During the whoie cycle, the changes in current take place ahead of the changes in voltage. Current and voltage are out of phase. because they do not incr€ase and decrease in the same direction at the same time. 3-5 AC FU~IDAMENTALS RE\11 EW 3. Capacitance (continued) + The sine waves shown in figure 3-3 represent the behavior of source voltage and current in a purely capacitive circuit -that is, a circuit in which resistance and inductance have no significant effects. Capacitance is the only factor that affects current and voltage. ln a pure1y capacitive circuit, capacitance causes current and voltage to be out of phase. Be- cause capacitance opposes a change in voltage, changes in current always occur dhead of chan~es 1n vo1tage. Another way to say tnis is co say that in a capacitive circuit, current leads voltage oy 90 degrees. 3-6 AC FUNDN-lEtfl ALS REV lEW 3. Capacitance (continued) '3-1. True or False. Capac1tance is a physical property of all AC circuits that opposes a change in voltage. 3-2. What 1s capacitive reactance? 3-3. Capacitive reactance is measured ir. 3-~. Circle the correct answer. A dielectric in a capacitor a. Increases the flow of protons to the positive terminal ~. Keeps electro~s from flowing from on~ p1ate to the other c. Aids electrons jn their flow from positive to negative d. Decreases the number of electrons on any plate 3-5. Befcre a capacitor can store energy, it must first be 3-6. True <Jr Faise. When a capacitor is fully charged, the source voltage and the voltage across the capacitor are equal in amount but opposite i n po l ar 1t y. 3-7. Capacitance causes (a)------and (b) out of phase. 3~ 7 ______ to be AC FJNDI\'4ENTALS REVIEW (continuea) 4. 1\C Power OBJECTIVES: • Differentiate between true power, reactive power, ana apparent power. • Explain nov.' power factcr 1s used in ca1ct.1atir.g true power in AC circuits. In DC circuits, i)Ower is equa 1 to vo 1 tuge l iraes current ( P = E I). The on 1 y facor that limits current in a DC circuit is resistance, so the only factors that affect DC power are current, voltage, and resistance. [n AC circ~its, however, inductance and capacitance must also be considered, so AC power calculations can be much more complicated than DC calculations. Because incuctance and capacitance cause AC current dna voltage to be cut of phase, there are three different kinds of power in AC circuits: true power, reactive power, anc apparent power. 4.1 True Power True power in an AC circuit is the power actually used to do work. The power used in a purely resistive circuit is true power. (A "purely resis- tive~ AC c1rcuit is one \n ~hicn inductance and capacitance are not large enough to be significant.) Figure 4-~ shows simplified voltage, cur- rE!nt, and true power sine waves for a purely resistive circuit. 4-l AC FUNDAMENTALS R~VIEw 4. AC Power (continJed) + Voltage and current Slne ·~aves like the ones sho·.:n in Figure 4-1 can be used to determine the true power in tne circuit at any instant. Tnis is done by ~rultiplying the voltage at any instant by current at that same iostant. Since voltage and current are in phase, they are both positive at the same time and negative at the same time. Therefore, their product, true power, will always be positive. since two positive numbers or two negative numbers multiplied together wi11 always yield a posittve result- positive po·wer. The ter'!l "positive power" is used as a convention. Positive power is power that is going to a load from a power source. Negative power, then, is power that is returning to a power source from a load. 4.2 Reactive Power Reactive power is the type of power tnat is found in a purely induct.1ve circuit or a purely ca)::acitive circuit. Un1 il:e tr:.~e power, reactive power aces no useful wen .. 4-2 2t AC FUNO~.ENTALS REVIE'..! 4. A: Power (cnntinued) Figure 4-2 shows simplified s1ne waves for voltage, current, and reactive power in a purely inductive circuit. Voltage and current are out of phase, with current 1agging behind voltage. + In the first quarter of the cycle represented in figure 4~2. voltage is positive and current is negative. Multiplying the two together will yield a negative va1ue, because the product of a positive number and a negative number is always a negative number. Tnus 1 at this point. voltage times current equals negative power. lJuring the second quarter of the cycle, voltage is still posit1ve, but current is now a 1 so positive. If voltage and current are mu 1t ip 1 i ed together durlng this portion of the cycle, the result is positive power. The same relation!>hips can be seem in the second half of the cycle. When voltage becomes nlilgative, current is still positive, so tne product of voltage and current is negdtive power. When voltage and current are both negative, in the final quiirter of the cycle. their product is positive power, because t'"'O negative numbers multiplieG together give a posit ve result. 4-3 - AC fUNO~~ENTALS RtVIEw 4. AC Pm•ter (continued) As cefined e3r1ier, positive power is power that goes from a power source to a load. In a purely inductive circuit, positive power goes from the power source to the inductance. The ir.ductance absorbs power from the power source as its magnetic flelc builds up. Negati~e power, as defined earlier, is power returning to the power source from a loaa. In an inductive circuit, the negative power periods are those during which the power absorbed by the 1nductance re:urns :o the power source as the mag- ~etic field collapses. As indicated oy tne sine waves in Figure 4-2, the amo~nt of power that is returned frcm the inductance to the power source is eQual to the amount of power that is supplied by the power source to the inductance. In a purely ind~cti.ve circuit, then, power just goes back and forth between the power source and the inductance. Since no power is used to do work, there is no power that can be identified as true power. The power in a purely induc- tive circuit is only reactive power. The power in a purely capac1tive circuit is also reactive power. FigJre 4-3 shOws voltage, current, an::l reactive power sine waves for a purely capacitive circuit. As was explained earlier, in a purely capaci- tive circuit, current leads voltage. 4-4 AC FUNDAf.',£NTALS P.EVIE' ... 4. AC Po¥fer (continued} During the first quarter of the cycle represented in Figure 4-3, both voltage and current are positive, so their product, power, is positive. ln the second quarter of the cycle, current is negative ana voltage Is posi- tive, so power is negative. Dur~ng the third quarter of the cycle, both current and voltage are negative, ~nich makes power positive ac;Jair1. Finally, in the last quarter of the cycle, current is positive and vo'tage is negative, so power is again negative. rna purely capacitive circuit, when power is positive, the capac1tor is charg i ny, o.o it is storing up power. When power is negative, the cap- acitor is discharging; it is returning power to the power source. The effect is the same for a purely capacitive circuit as for a purely induc- tive c1rcuit: the amount of power that is supplied by the power source to the capacitor is equal to tne amo-.~nt of power that is returned frml the capacitor to the power source. The power in a capacitive circuit does no~ do any work, so it is reactive power rather than true power. 4.3 Apparent ?ower Apparent power is the power used to do work plus the power stored durlng part of a cycle by inductance and capacitance and then returned to the power source. Apparent power is voltage times current in any circc~it. {In a purely resistive circuit, apparent power and true power are the same.) Figure 4-4 shows a circuit that includes a power source, a resistor, an inductor, and a capacitor. The product of voltage times current in this circuit cannot be the true power of the circuit, because true power can be calculated this way onty for purely resistive circuits. The product cannot be reactive power, either, because there. is a resistor 1n the circuit. The product of voltage times current in this circuit is apparent power. 4-5 AC FUNDAMENTALS REVIEW 4, AC Power (continued) 4.4 Power factor In a circuit like the one shown in Figure 4-4, the effects of resistance, inductance, and capacitance must all be considered in determining true power. Taken together, the combined effect of these three f<ictors on current flow and, therefore, on power, is called impedance. Impedance can be ca1cu1ated, but this is not done very often by maintenance personnel. In most cases, the true power in an AC circuit that is affected by im- pedance is calculated with the aid of the power factor associated with the specif1c circuit. The power factor for an AC circuit is the rat1n of the true power to the apparent power in that circuit. Power factor is usually expressed as a decimal value. Power factor is used as follows: When the apparent power of a circuit and the power factor for that circuit are known, true power is. calculated by multiplying the apoarent power times the power factor. In other words, the true power in an AC circuit is equal to vo1tage times current times the power factor. ln mathematicul terms, tnis is expressed asP"' Ex 1 x PF. 4-6 AC FUNDAMENTA-.S REVIEW 4. AC Pm1er (continued) Questions 4-~. TrJe or False. True power is the amount of power actually ..!Sea to do work. 4-2. Circle the correct answer. Positive power is power that is a. b. r ~. d. Going to a lead from a power source Returning to a power source from a loaa The product of a negative current and a positive voltage Equal to voltage times res1stance 4-3. Reactive power is power thilt oo useful work . ..,.( ...,.do_e_s_.___,d_o_c_s_n_o-.t,..; 4-4. The voltage ano current sine waves for reactive po·,.,er are always phase. 1 in, out of J 4-5. True or False. Apparent power is the res~lt of mult1plying voltage times current in any circuit. 4-6. The comoined effect of resistance, inductance, and capacitance en current flow in an AC circuit is called 4-7. ln most cases, true pol't·er in AC circuits is caiCLJlated 'lli'th the aiu of the _____ associatea with the specific circuit. 4-8. Tne power factor for a certa1n AC circuit is .8. If the vo1tage is 480 \iolt;, ana the current is 50 amps. what is the true power used by the circuit? 4-7 AC fUNDJl.MENTALS REV I E\oi 4. AC Power (continued) 4-9. Given the fol1owing values, calculate tru~ power. E = 110 volts 10 amps PF .5 4-8 AC FlJNDANEt-;TALS REVIEW (contir:uec} 5. Single~Phase and Three-Phase Systems OBJECTIVES: • Explctin the differenc~: between single-phase ana tnree phase AC systems. • Explain how a tnre~-w~re single-phase A~ system su~plies two different voltages. • Differentiate between delta-connected and wye-connected three-phase AC systems. There are two comnon types of AC power systems: single-phase systems and three-phase systems. Tne purpose of this segment is to introduce some terms that are associated with these syste;r,s. i\ simplified single-phase system is illustrated in Figure 5-l. IL cor.- sists of two wires, a voltage source, and a load, which is represented by a resistor. 5-1 AC fUiWANENTALS RE'II&i 5. Single-Phase and Three-Phase Systems (continued) A simplified three-phase system is shown in Fig1.1re 5-Z. This system consists of three wires, a voltage source (indicated by the three coils in the circle}, and a load (indicated by the three resistors). 5.1 Single-Phase Systems Single-phase systems are the most comonly used AC power systems for general electrical needs. There ~re two ba~ic types of single-phase sys- tems: the two-wire system and the three-wire systen. ln the two-wire system, the voltage supplied has only one value. Since it is often desir- able to have more tnan one voltage for home and office use, the three-wire systern was developed. The three-wire system makes it possible to have two different voltages from one voltage source. 5-2 AC fUNDA.'>lENT ALS REV 1 E\oi 5. Single-Phase and Tnree-Phase Systems (continued) The component that changes a two-wire system into d three-wire system Is a transformer. As Figure 5-3 illustrates, in a three-wire system, two 1ines come into the transformer on the primary side, and three lines come off toe transformer on the secondary side. The middle line on the secondary side js called the neutral line. Voltage between the neutral line and either the top line or the bottom line is 110 volts. Voltage between the top and bottom lines is 220 volts. Thus, it is possible to get either 110 volts or 220 volts from tnis three-wire system. Because the three-wire system provides more than one voltage, it has many applications for general elec- trical use. One of the lines in a two-wire system and the neutral line in a tnree-wire system are usi.ially grounded as a protective measure. Then. if an un- grounded line ace i dent a lty becomes grounded, a short circuit will occLr and the circuit's fuses or circuit breakers will open the circuit. 5.2 Three-Phase Systems Three-phase systems arc most often found in large inaustrial installations where large amounts of power are used. The two types of connections coi!Tl1on 1y used for power sources and for loads Hl three-phase systems are delta connections and wye connections. Single-?hase a~8 Three-?hase Systems (continued) 5.2.1 Connections Figure 5-4 show:s t.he wiring for a delta ccrmection. In this examp1e, the three coils represent a three-phase transformer. The ends of each coi I are ~onnected to the ends of the other two coils. The three wires comins out Df the transformer are connected to Lhree r·e sis tors, wh 1 ch are a 1 so de I ta~~ cor:nected. The current a;"JC voltage in the coils and the resistors of a system like this are not always the same as the current and voltage in the wires. The current that flows through the coils or resistors is called phase current. The voltage that is applied across the resistors or induced i~ the coils )s called phase voltage. The current that flows through the wires 1s callej line current, ard the voltage that is applied to the wires is called line voltage. In a delta-connected system, the phase voltage equals the line voltage, but the phase current does not equa; the line current. Each coil or resistor shown 1n Figure 5-4 is connected across two wires. Therefore, the voltage In ea~h coil or resistor (tne phase voltage) is equal to the voltage in the wi ~es (the 1 i ne vo I tage). However, the ends of two coils, or two res is tors, are connected to one wire, so the ~hase currents ada together to form 5-4 l\C F :.J;!OA/>IEi1 T.4i..S I'EV IE"' 5. S'ngle-?ilase anu T.'1n:e-Phase Syster;JS (continued) the 1ine current. The line current is actually equal to the sq~are root of three (wh1ch is 1.73) times the phase current. Therefore, multiplying the ~nase current times 1.73 equals the line current. The relationsnips between voltage and current in a delta connected system can be sunlra""i;:ed in tne following formulc.s: E ? In these formulas, E1 is tilE line vo 1 tage, £p 1S the phase voltage, IL is the line cur~ent, and Ip is the phase current. 5.2.2 ~ve Connections The wiring for a ty,Jical wye-connected three-phase system is st1own in Figure 5-S. (A wye connection is also known as a star connection.) Ir: a wye connected system, one end of each coi1 or resistor is connected to one eno of both of the other coils or resistors. The free ends of the coils or res1stors are connecte~ to the three phase lines. 5-5 AC FUNDAMEr,TALS R::.~·r:w 5. Single-Phase anc Three·Phase Syste.71s (continued) Wye connections have different effects on voltage and current than delta connections do. :n a wye-connected systen, the phase currenL is equal to the line current, but the phase voltage 1s not equal to the line voltage. As shown in Figure 5-4, tne current thaL flows through each 1ine lias to flow through the coil or the resistor in the line. Therefore, t~e current in a wye-connecteo syslem cannol split or add togetncr the wa:; it does in a delta-connected system. However, the voltage in each coil or resistor (lne phase vo1tage) has to be added to the voltage in on<! of the other coils 'lr resistors to form the voltage across any two wires (the line voi:agc). :n wye-connectec systems, the phase vo<l tage times 1. 73 equa 1 s the 1 i ne vo It- age. The re 1 ati ons hips bet•,;een voltage ana current in a wye-connected system can be summarized in the following formulas: E. In these formulas, is the line voltage, Ep is the pnase vo1tase. IL is the line current, and Ip is the phase current. Questions 5-L The component that cnanges a two-wire single~phase system into a three-wire sing1e phase system is a ------- 5-2. Circle the correct answer. The rniodle line 011 the seconc:Jary side of a three-win: single-phase system is a. Ca1led the neJtral line b. Connected in a delta pattern c. Never used a. 110 volts 5-6 AC FUN DPJ~ENT ALS REVIEW 5. Single-Pr1ase and Three-Pnase Systems (continued) 5-3. Ir a three-phase system, the current:. that. flows through the coils or resistors is called current. T!)Fiise-;--y; neT 5-4. True or False. h a delta-connected system, phase voltage equals line voltage, but phase current does not equal line current. 5-5. To calculate the line voltage of a wye-connected three-phase system, mu1 tiply the phase voltage by-------- 5-6. In a wye-connected three-phase systerr., phase crrrent and line cur- rent are ~=--=:-r--~:-:-:""'"T ( equa 1 , unequa T) Section 12 Electrical Safety Requirements This section sets forth requirements for electrical safety. It specifically addresses working in restricted areas; working near exposed energized overhead lines or parts; operating equipment near radio and microwave transmission towers; working on electrical equipment and systems; personal protective grounding; temporary wiring; disconnect and overcurrent protection; ground- fault protection; hazardous locations; wet locations; and battery charging. 12.1 General Electrical Safety Requirements All electrical work practices must comply with applicable sections of the Occupational Safety and Health Administration (OSHA), National Fire Protection Association (NFPA), National Electrical Code, National Electrical Safety Code, and State adopted electrical codes. 12.1.1 Approval Required. Use only electrical wire, conduit, apparatus, and equipment for the specific application that is approved or listed by Underwriters Laboratories (UL), or Factory Mutual Corporation (FMC). Install and use listed, labeled, or certified equipment according to the instructions included in the listing, labeling, or certification. 12.1.2 Qualified Persons. Only qualified personnel familiar with code requirements, safety standards, and experienced in the type work may work on electrical circuits and equipment. NFPA 70E and OSHA 29 CFR 1910.269 contain references for training requirements. See attachment at the end of this section. 12.1.3 Safety Requirements Before Performing Electrical Work. The employer will determine, by inquiry, direct observation, or instruments, the location of any part of an energized electric power circuit, exposed or concealed. If the work may cause any person, tool, or machine to penetrate the boundaries set forth in table 12-1, de-energize the circuit(s) and ground them, as appropriate. A clearance may also be required. Additionally, all of the following must be required: a. Underground Lines. Protect all underground lines with surface signs and a longitudinal warning tape buried 12 inches to 18 inches above the lines. Do not perform drilling, auguring, or material excavating operation within 6 feet of underground lines unless the lines have been deenergized. b. Job Briefing. The supervisor or designee must conduct a job briefing with affected workers. The ~upervisor or designee must hold additional job briefings if significant changes occur during the course of work The briefing must cover the following: 119 First Aide CPR Reclamation Safety and Health Standards (1) Job Hazard Analysis (JHA). Identify all hazards associated with the job in a written JHA and discuss them. (2) Nonelectrical Hazards. Identify, in a written JHA, hazards not associated with the electrical work but expected to be encountered, and discuss them. (3) Personal Protective Equipment (PPE). Provide and use the appropriate PPE needed to accomplish the job safely. Use flash-protection clothing in accordance with NFPA 70E if the job requires operating, racking, circuit breakers with the doors open, or, working within reaching distances of exposed energized parts. Employees working pn energized lines and equipment rated at 440 volts or greater must use rubber gloves, hard hats, safety boots, and other approved protective equipment or hat-line tools that meet ASTM standards. 12.1.4 Other Procedures. Perform procedures related to electrical work in accordance with the following: • FIST 1-1, Hazardous Energy Control Program FIST 5-1, Personal Protective Grounding, and • Written Standard Operating Procedures (SOPs) of each area office 12.2 Restricted Areas 12.2.1 General. Provide effective barriers or other means to ensure that people do not use areas with electrical circuits or equipment as passageways when energized lines or equipment are exposed. Effectively guard live parts of wiring or equipment to protect persons or objects from harmful contact. Use special tools insulated for the voltage when installing or removing fuses with one or both terminals energized. 12.2.2 High-Voltage Equipment (over 600 volts nominal). Isolate exposed high-voltage equipment, such as transformer banks, open switches, and similar equipment with exposed energized parts to prevent unauthorized access. Isolation must consist of locked rooms, fences or screened enclosures, walls, partitions, or elevated locations. Keep entrances to isolated areas locked when not under constant observation. Post DANGER-IDGH VOLTAGE warning signs at entrances to these areas. Properly ground conductive components, fences, guardrails, screens, partitions, walls, and equipment frames and enclosures. 12.2.3. Temporary Fences. When extending a fence or removing it for work on high voltage equipment, erect a temporary fence of comparable construction and protection. Electrically bond the temporary fence to the existing fence. If the fence is more than 40 feet long, bond posts to the ground mat at no more than 40-foot intervals. Bond posts at each side 120 Section 12-Electrical Safety Requirements of gates or openings to the ground mat/grid and install a bonding jumper across all gate hinges. Bond all corner posts to the ground mat. 12.2.4 Perimeter Markings. Use approved perimeter markings to isolate restricted areas from designated work areas and entryways. Erect them before work begins and maintain them for the duration of work. Approved perimeter marking must be: a. Barrier Tape. Install red barrier tape printed with the words "DANGER-HIGH VOLTAGEu around the perimeter of the work area and accessway approximately 42 inches above the floor or work surface. b. Synthetic Rope Barrier. Install a barrier of yellow or orange synthetic rope 36 to 45 inches from the floor with standard danger signs of non-conductive material attached at 10-foot intervals containing the words "DANGER-IDGH VOLTAGE". 12.3 Working Near Exposed Energized Overhead Lines or Parts 12.3.1 General. For troubleshooting and testing purposes only, qualified persons using proper test equipment and personal protective equipment must adhere to the boundaries shown in figure 12-1 and specified in table 12-1. For adjusting, tightening, calibrating or any other work, the circuits must be de-energized, or employees must use voltage-rated gloves and voltage-rated insulated tools. 12.3.2 Low Voltage Testing. For low voltage troubleshooting and testing purposes only, i.e., under 480 volts, a qualified person may penetrate the prohibited approach boundary shown in table 12-1, column 5, with test instrument probes, leads, ct' s, etc. The qualified person must wear Class 00 ( 500 volt-rated) gloves. 12.3.3 Unqualified Person Restrictions. When a person without electrical training works on the ground or in an elevated position near overhead lines or any other exposed energized parts, supervisors and employees must ensure that the unqualified person and the longest conductive object they might contact or handle, can never come closer to any Figure 12-1.--Boundarie&. 121 Reclamation Safoty and Health Standards energized line or part than those distances listed in table 12-1, column 2, for energized lilies or column 3 for other exposed live parts. Table 12-1.-Approach boundaries to exposed energized conductors/parts for qualified employees (All dimensions are distances from energized conductor/part to employee) (1 (2) _@ _i~ _i~ Limited approach boundaries Restricted approach Nominal voltage phase boundary Prohibited to phase, or single Exposed moveable Exposed fixed indudes inadvertent approach phase conductor circuit part movement boundary Oto 50 not specified not specified not specified not specified 51 to 300 10-ft 0-in 3-ft 6-in avoid contact avoid contact 301 to 750 10-ft 0-in 3-ft 6-in 1-ft 0-in O-ft 1-in 751 to 15 kV 10-ft 0-in 5-ft 0-in 2-ft 2-in O-ft 7-in 15.1 kV to 36 kV 10-ft 0-in 6-ft 0-in 2-ft 7-in O-ft 10-in 36. 1 kV to 46 kV 10-ft 0-in 8-ft 0-in 2-ft 9-in 1-ft 5-in 46.1 kV to 72.5 kV 10-ft 0-in 8-ft 0-in 3-ft 3-in 2-ft 1-in 72.6 kV to 121 kV 10-ft 8-in 8-ft 0-in 3-ft 2-in 2-ft 8-in 138 kVto 145 kV 11-ft 0-in 10-ft 0-in 3-ft 7-in 3-ft 1-in 161 kV to 169 kV 11-ft 8-in 11-ft 8-in 4-ft 0-in 3-ft 6-in 230 kV to 242 kV 13-ft 0-in 13-ft 0-in 5-ft 3-in 4-ft 9-in 345 kV to 362 kV 15-ft 4-in 15-ft 4-in 8-ft 6-in 8-ft 0-in 500 kV to 550 kV 19-ft 0-in 19-ft 0-in 11-ft 3-in 10-ft 9-in 765 kV to 800 kV 23-ft 9-in 23-ft 9-in 14-ft 11-in 14-ft 5-in Notes: This table is taken from NFPA 70E table 2-1.3.4 and OSHA 29 CFR,1910.269 table R6. Limited Approach Boundaries. A shock protection boundary to be crossed only by qualified persons (at a distance from a live part). Unqualified persons must not cross this boundary unless accompanied by a qualified person. Restricted approach Boundary. A shock protection boundary to be crossed only by qualified persons (at a distance from a live part). The boundary's proximity to a shock hazard requires the use of shock protection techniques and equipment v.tlen crossed. Prohibited Approach Boundary. A shock protection boundary to be crossed only by qualified persons (at a distance from a live part). When crossed by a body part or object, this boundary requires the same protection as if direct contact is made with a live part (i.e., requires voltage rated tools and voltage rated gloves and, in some cases, other voltage rated clothing). 122 Section 12~-Electrical Safety Requirements ?··.~ i'-A A/;/"./'-..,<,."-/""./'-./ \· .. ·.·} ~ (r L~' -\\ ~ 1: ~ ,._ . . .• ·, ::~ Do not ser11ce equipment :. opposite each c:*her at · H Minimum 30in the same t!rne • • Electrical ~ • Electrical sw~ch-!' r switch- 0 0 0 board J.,.__,_3~.5-""ft ---Jio-4 board :': Botted/f' 4801277 ~ ) 4801277 .l Panels j ·~ .. 3.5fl BoHed _.-Panels Figure 12-3.-Working space requirements for rear or side access. c. Doors and hinged panels. Doors and hinged panels must have at least at least a 90- degree opening. Keep working space clear at all times. Do not store parts, tools, and equipment (see figure 12-4). 12.5.4 Passageway Barriers. Provide effective barriers or other means (barrier tape) to ensure that areas containing electrical circuits or equipment are not used as passageways when energized lines or equipment are exposed for testing or maintenance. This includes open doors on motor control centers, and switchgear. 12.6 Personal Protective Grounding 12.6. 1 General. Qualified persons must comply with applicable provisions of FIST Volume 5-1 "Personal Protective Grounding." Include written grounding procedures in all clearances, special work permits, etc. The JHA must include the procedures, and employees must discuss them before beginning work. 12.6.2 Over 600 Volts. Place groWids as close as possible to the work and within sight of the workers Panel board 30 in. -t----1.,.1 1+--30 in. ---t.-.,..1 Figure 12-4.-Working space requirements for doors and hinged panels. 127 EMERGENCY CONTACT LIST contact List for Accidents, Fire, Natural Disasters, or any other Emergency Public Health Nurse VPSO Mayor Ci'ty office Supervisor Plant Operator Phone Number Periodic Review of Instructions Review of instruction given in SOP's and regional supplements to FIST Vol. 1.1 should be conducted at least annually to assure that the documents are complete and up to date. As discussed above, SOP's shall be annually certified as being current by the Regional Director. TRAINING OF O&M PERSONNEL Need For Training More advanced designs of generators, transformers, and breakers, and associated automatic, semiautomatic, and remote supervisory control equipment are being installed in Reclamation stations; therefore, operating problems are becoming more complex. Uninterrupted service is a necessity, as even a brief outage of electrical service may result in considerable loss to some power consumers as well as loss of revenue and prestige to Reclamation. Only skilled and well-trained personnel can perform the tasks necessary for efficient, economical, and safe operation of facilities. A continuing training program will assist our O&M personnel in becoming better informed, more alert, and more safety conscious. Training of Operators and Switchmen As new personnel are employed to assist experienced operators, it is essential that they not only receive basic training regarding equipment, but also have the opportunity for training which will qualify them to fill more responsible positions as these become vacant As plants and facilities become more complex, it is desirable that key operating positions be filled by employees who have a background of experience and training. The most efficient and experienced operators should be advanced in the Reclamation's organization to the positions of operating supervisors as they develop operating skills and gain background experience and knowledge in operations. Three separate and disti net training programs are carried on concurrently for operating personnel to improve their knowledge of the operating principles of the electrical and 5 POWER SYSTEM CLEARANCE PROCEDURE January 1989 Western Area Power Administration Power System Operations Manual Chapter 1 Bureau of Reclamation F acilities/lnstructions/Standards{f echniques FIST Volume 1-1 United States Department of Energy Western Area Power Administration Golden, Colorado United States Department of Interior Bureau of Reclamation Denver, Colorado .. CONTENTS Page Preface ....................................................................... . Section I. Introduction ................................................................ 1 II. Definitions .................................................................. 4 Ill. General responsibility and authority ........................... 9 IV. Materials for ·use with these procedures and instructions ........................................................ 11 V. Clearances ............................................................... 25 VI. Hot Line Orders ........................................................ 36 VII. Special Condition .................................................... .42 VIII. Danger Tags ............................................................. 43 IX. Tagging of equipment operated by supervisory control .............................................. 45 - X. General Switching ................................................... .46 XI. Operations associated with contractors or non-Agency forces ........................... .47 XII. Operations associated with non-Agency maintenance forces .............................. 51 XIII. Operations associated with Interconnected Systems ........................................... 53 XIV. Instructions for Power System Switching ................. 57 XV. Index ........................................................................ 61 UNITED STATES DEPARTMENT OF ENERGY WESTERN AREA POWER ADMINISTRATION IIJR£AU 01' RECLAUATIOH UNITED STATES DEPARTMENT OF THE lNTRIIOR--BUREAU OF RECLAMATION ~~- SWITCHING PROGRAM FORM II:I,)VEST fOH: u ~ UllLO usc uo.s STATIOH(Sl EQUIPMENT UKEH OUT OF SERVICE R£9UtREO Tt~£ DATE WORK TO BE PEHtOKMtu REQUESTED 8Y 0 BE ISSUED 10 MOTIF ItA T ION HI IHHtH5 MAUl fXPECTED DURA Tl<ll J~TIMATED Wit TO REruRII £QUI Ao!ENT TO SfRVICE IN O!ERGDICY ~!_IIi"'"" run ""'"'"uotlil PREPAR£D IT CK£CK£D 8Y PREPARED BY I CHECKED BY II( TA I LUI :~WI r~ IIIIi AIIU Eyut IM£11 TAG 110 TIME PERFOAMEO BY TAG KO --------·-----------·-----··-----i--r--·-·-------------+---t----- _____ _;_ __ ;.._ _______ -t---11-------------------------·-----·----· -·- ----------------~---+----r-------~----r-----------------------1---·---- ·-------·--------------· -· ....... -.. ·1-·--r-------·-··-... -·-··------t---1----····--· -----·-----·-. ----· .. -+---+---t-----1---------------------+----+--- -... --· --·-·-------· -······-·--· __ ...... _ ··-.... _ ·---... . . -t- _. __ ...... -----... --------·------1--·--·-------·-... . ·-·-----·------------+---+----- -----.... --... -.. ----··-· ----··-...... --·--1-------·· ..... . ----------·--------c---t------ .... -----------------·-1-------____ ,. __ --·-·--·---------t---t------· --·-------------------r---·-1--·---· .. -·-··---·---··-----1----11------+----+-------------------~--···---· t- --------·----.... -... ---1--------·-r------.--· ---· .. ·-1--·------·-----------1----r----- -----------·--------·------·-+--+----1---+--------------r-------·--. ----·-··--··------·-----· ________ ,.. --·-----··· -----···-· --· 1-----------------·---------·- ··-----------.. --+-~ ----------· ··-r-·--·---------------+--+---- ISSUED lO ISSUED BY TIHE OAT£ HO. RFo FASHI TO TIM£ DA Tt ...... ·1----···-----..... ··-1--·--·--·-··--·--· t--··---· ·-r---·-··--··-----;,..------------+-----+------- Figure 1 (NOT USED BY WESTERN) U. S. DEPARTMENT OF THE INTERIOR BUREAU OF RECLAMATION POWER PLANT SWITCHING ORDER S 0 NO. __ CLEARANCE NO.------ISSUED TO -------- STATION-------------------- ORDER RECEIVED ___ M --------19 __ _ REC'D. FROM--------REC'D. BY _______ _ SAFETY TAG NO. ORDER ORDER DETAIL EXECUTED BY: •· Figure 2 SWITCHING ORDER FORM 15 TIME I I ! I I I I I . I Sta:tor ·Generator· t ·urblne ~BBnarator Shaft Induction generator From Wikipedia, the free encyclopedia Jump to: navigation, search An induction generator is a type of electrical generator that is mechanically and electrically similar to a polyphase induction motor. Induction generators produce electrical power when their shaft is rotated faster than the synchronous frequency of the equivalent induction motor. Induction generators are often used in wind turbines and some micro hydro installations due to their ability to produce useful power at varying rotor speeds. Induction generators are mechanically and electrically simpler than other generator types. They are also more rugged, requiring no brushes or commutators. Induction generators are not self-exciting, meaning they require an external supply to produce a rotating magnetic flux. The external supply can be supplied from the electrical grid or from the generator itself, once it starts producing power. The rotating magnetic flux from the stator induces currents in the rotor, which also produces a magnetic field. If the rotor turns slower than the rate of the rotating flux, the machine acts like an induction motor. If the rotor is turned faster, it acts like a generator, producing power at the synchronous frequency. In induction generators the magnetising flux is established by a capacitor bank connected to the machine in case of stand alone system and in case of grid connection it draws magnetising current from the grid. It is mostly suitable for wind generating stations as in this case speed is always a variable factor. [edit] See also • Electrical generator [edit] External links • Asynchronous generator Retrieved from "http:/ I en. wikipedia. org/wiki!Induction___generator" Categories: Electrical generators Views • A11icl~ • Discussion • Edit this~ • History Cogeneration Technologies An EcoGeneration Solutions LLC. Company E-mail: info@ cogeneration .net Tel. (832) 758 • 0027 Cooler, C'Jeaner, r;ree11er Power & Ene':Ef.V Solutions Syn~hronous Generators www.SynchronousGenerators·.com What is a Synchronous Generator? Home Contact Us l Links A "synchronous" generator runs at a constant speed and draws its excitation from a power source external or independent of the load or transmission network it is supplying. A synchronous generator has an exciter that enables the synchronous generator to produce its own" reactive" power and to also regulate its voltage. Synchronous generators can operate in parallel with the utility or in "stand-alone" or "island" mode. Synchronous generators require a speed reduction gear. Customers worried about future blackouts and having increased power reliability should only consider cogeneration and trigeneration power plants that have SYNCHRONOUS generators. Additionally, systems with synchronous generators can provide up to 100% of the facility's power, whereas induction generators can only supply about 1/3 of the facility's power requirements. What is an Induction Generator? An "induction" generator is essentially a special purpose motor that is run slightly above synchronous speed by the turbine. Induction generators receive their excitation from the grid, or electric utility and they have no means of producing or generating voltage until such time the generator is connected to the grid. Induction generators are direct-drive. The frequency and voltage of the power generated with induction generators are governed by the frequency and voltage of the incoming electric utility line. Induction generators can ONLY be run in parallel with the grid, which means when the electric grid goes down, or there is a blackout, ALL gensets, cogeneration and trigeneration power plants within the grid that has the blackout, also go down. This is why customers seeking greater power reliability should only consider cogeneration and trigeneration power systems that have SYNCHRONOUS generators. Transformer From Wikipedia, the free encyclopedia Jump to: navigation, search For other II \1 ',\_ see i 'I ~1,1, jill n':lJ' Q:J Three-phase pole-mounted step-down transformer. A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled electrical conductors. A changing current in the first circuit (the primary) creates a changing magnetic field; in turn, this magnetic field induces a changing voltage in the second circuit (the secondary); this is called mutual induction. By adding a load to the secondary circuit, one can make current flow in the transformer, thus transferring energy from one circuit to the other. The secondary induced voltage Vs, of an ideal transformer, is scaled from the primary Vp by a factor equal to the ratio of the number of turns of wire in their respective windings: By appropriate selection of the numbers of turns, a transformer thus allpw~ an alternating voltage to be stepped up-by making Ns mor~ than Np-or stepped 'down, by making it less. · Transformers are some of the most efficient electrical 'machines',w with some large units able to transfer 99.75% of their input power to their output.ill Transformers come in a range of sizes from a thumbnail-sized coupling transformer hidden inside a stage microphone to huge units weighing hundreds of tons used to interconnect portions of national power grids . All operate with the same basic principles, although the range of designs is wide. Contents • 1 Applications • 2 Basic principles o 2.1 Indu<jion lcr~.Y o 2.2 Ideal power equation o 2.3 Detailed operation • 3 Practical considerations o 3. I Leakage flu~ o 3.2 Effect of frequenc_x o 3.3 Energy losses • 4~gillvalent circuit • 2-_Types o ilh.utotransformer o 5.2 Polyphase transformers o 5.3 Leakage transformers o ~.,:1 Resonant tramfQrtn§I~ o 5. 5 Instrument transformers • §_ Clit~~ficrui9_r1 • L.C __ QJls1mc_tign o .LLC:m~~ • ]_.j_,_lJ~aminjlted steels_p...r__e~ • 7_,_L.f.._S_Qii<i cor~~ • Il.l. T or.9idal ~or~~ • LL4. Air cores o 7.2 Windings o 7.:U:JJolam: o l4 _I§WJina~ • 8 Histoey • 2.._See alsg • lQ Not__e~ • l l Reference~ • 12 External link~ [edit] Applications A key application of transformers is to increase voltage before transmitting electrical en~ over long distances through }Vir§~. Wires have resistanc~ and so dissipate electrical energy at a rate proportional to the square of the current through the wire. By transforming electrical power to a high-voltage (and therefore low-current) form for transmission and back again afterwards, transformers enable economic transmi~sion_Qf po~~er over long distances. Consequently, transformers have shaped the ~lectricity_§l!P.W.Y industry, permitting generation to be located remotely from points of demand. m All but a tiny fraction ofthe world's electrigaiJlQW..§J: has passed through a series of transformers by the time it reaches the consumer.w Transformers are used extensively in electronic products to step down the supply voltage to a level suitable for the low voltage circuits they contain. The transformer also electrically isolates the end user from contact with the supply voltage. Signal and audio transformers are used to couple stages of amplifiers and to match devices such as microphones and record player cartridges to the input ir:n~dan<;:~ of amplifiers. Audio transformers allowed telephone circuits to carry on a twQ::.'Y<!Y col1\<'ersation over a single pair of wires. Transformers are also used when it is necessary to couple a differential-mode signal to a ground-referenced signal, and for isolation between external cables and internal circuits. [edit] Basic principles The transformer is based on two principles: firstly, that an electric current can produce a magnetic _tielc! (electromagnetism) and secondly that a changing magnetic field within a coil of wire induces a voltage across the ends ofthe coil (~l~JLomggnetic induction). By changing the current in the primary coil, it changes the strength of its magnetic field; since the changing magnetic field extends into the secondary coil, a voltage is induced across the secondary. Primary winding .~;: tuth~ Secondary winding An ideal step-down transformer showing magnetic flux in the core A simplified transformer design is shown to the left. A current passing through the primary coil creates a JJJ.M..~tic _field. The primary and secondary coils are wrapped around a 9QI~ of very high magneticpenneahlliiY, such as iron; this ensures that most of the magnetic field lines produced by the primary current are within the iron and pass through the secondary coil as well as the primary coil. [edit] Induction law The voltage induced across the secondary coil may be calculated from Faraday's law of indLLCtion, which states that: where Vs is the instantaneous voltage, Ns is the number of turns in the secondary coil and @equals the magnetic flux through one turn of the coil. If the turns of the coil are oriented perpenpicular to the magnetic field lines, the flux is the product of the magnetic fielQ strength B and the area A through which it cuts. The area is constant, being equal to the cross-sectional area of the transformer core, whereas the magnetic field varies with time according to the excitation of the primary. Since the same magnetic flux passes through both the primary and secondary coils in an ideal transformer,m the instantaneous voltage across the primary winding equals \ T !\' d<P lp = ~ 'p-dt Taking the ratio of the two equations for Vs and Vp gives the basic equationill for stepping up or stepping down the voltage 1Vs [edit) Ideal power equation &"J The ideal transformer as a circuit element If the secondary coil is attached to a load that allows current to flow, electrical power is transmitted from the primary circuit to the secondary circuit. Ideally, the transformer is perfectly efficient; all the incoming energy is transformed from the primary circuit to the magnetic field and into the secondary circuit. If this condition is met, the incoming electric power must equal the outgoing power. Pmcoming /pVp Poutgoing = fsVs giving the ideal transformer equation 1/ ~· s j\T l'f's -=--= If the voltage is increased (stepped up) (Vs > Vp), then the current is decreased (stepped down) (Is< /p) by the same factor. Transformers are efficient so this fo~ula is a reasonable approximation. The impedance in one circuit is transformed by the square ofthe turns ratioLil For example, if an impedance Zs is attached across the terminals of the secondary coil, it ( ) ? Z"' Np - appears to the primary circuit to have an impedance of 5 N...... . This relationship is reciprocal, so that the impedance Zp of the primary circuit appears to the secondary to be Z (1":s) 2 p l''p [edit] Detailed operation The simplified description above neglects several practical factors, in particular the primary current required to establish a magnetic field in the core, and the contribution to the field due to current in the secondary circuit. Models of an ideal transformer typically assume a core of negligible t~luctans::~ with two windings of zero resihlp_nc;;,;. f(,J When a voltage is applied to the primary winding, a small current flows, driving _flu2; around the magnetic circuit ofthe core.I2l. The current required to create the flux is termed the magnetising current; since the ideal core has been assumed to have near-zero reluctance, the magnetising current is negligible, although still required to create the magnetic field. The changing magnetic field induces an ~l§ctromQtiveJorq; (EMF) across each winding.m Since the ideal windings have no impedance, they have no associated voltage drop, and so the voltages Vp and Vs measured at the terminals ofthe transformer, are equal to the corresponding EMFs. The primary EMF, actin~ as it does in opposition to the primary voltage, is sometimes termed the "back EMP_U!I This is due to L~.:nz'sJiJ.lY which states that the induction ofEMF would always be such that it will oppose development of any such change in magnetic field. [edit] Practical considerations [edit] Leakage flux Primary YWldlnll. i Leaka'ge fluxi Secondary winding ~+ ~--/ )J l;J Leakage flux of a transformer Main article: Leakage inductans:g_ The ideal transformer model assumes that all flux generated by the primary winding links all the turns of every windin~ including itself. In practice, some flux traverses paths that take it outside the windings. 9 Such flux is termed leakage flux, and results in ls;akage inductanc~ in ~eries with the mutually coupled transformer windings.llil Leakage results in energy being alternately stored in and discharged from the magnetic fields with each cycle of the power supply. It is not directly a power loss, but results in inferior voltage regulation, causing the secondary voltage to fail to be directly proportional to the primary, particularly under heavy load.I21 Transformers are therefore normally designed to have very low leakage inductance. However, in some applications, leakage can be a desirable property, and long magnetic paths, air gaps, or magnetic bypass shunts may be deliberately introduced to a transformer's design to limit the short-circuit current it will supply.11H Leaky transformers may be used to supply loads that exhibit negative resistance, such as ~lectric arcs, mercury vapor lan_:m§, and neon signs; or for safely handling loads that become periodically short-circuited such as _ylectri~rcwelders.UQ! Air gaps are also used to keep a transformer from saturating, especially audio-frequency transformers in circuits that have a direct current flowing through the windings. [edit] Effect of frequency The time-derivative term in Faraday's Law shows that the flux in the core is the integral of the applied voltage.lill Hypothetically an ideal transformer would work with direct- current excitation, with the core flux increasing linearly with time.ml In practice, the flux would rise to the point where magnetic saturation of the core occurred, causing a huge increase in the magnetising current and overheating the transformer. All Bractical transformers must therefore operate with alternating (or pulsed) current. 111 Transformer universal EMF equation If the flux in the core is sin~,Lsoidal, the relationship for either winding between its m~ Voltage of the winding E, and the supply frequency f, number of turns N, core cross- sectional area a and peak ma~_li: flu_,x demity B is given by the universal EMF . liil equatton: 21r f iVaB _ E = . 10 = 4.44fJ.\' aB """ The EMF of a transformer at a given flux density increases with frequency_l<>l By operating at higher frequencies, transformers can be physically more compact because a given core is able to transfer more power without reaching saturation, and fewer turns are needed to achieve the same impedance. However properties such as core loss and conductor skin etiect also increase with frequency. Aircraft and military equipment employ 400 Hz power supplies which reduce core and winding weightLLll Operation of a transformer at its designed voltage but at a higher frequency than intended will lead to reduced magnetising current; at lower frequency, the magnetising current will increase. Operation of a transformer at other than its design frequency may require assessment of voltages, losses, and cooling to establish if safe operation is practicaL For example, transformers may need to be equipped with "volts per hertz" over-excitation reliJY_§ to protect the transformer from overvoltage at higher than rated frequency. Knowledge of natural frequencies of transformer windings is of importance for the determination of the transient response of the windings to impulse and switching surge voltages. [edit] Energy losses An ideal transformer would have no energy losses, and would be 100% efficient In practical transformers energy is dissipated in the windings, core, and surrounding structures. Larger transformers are generally more efficient, and those rated for electricity distribution usually perform better than 98%_illl ExperimeJ!tal transformers using .1'JJQ.erconducting windings achieving efficiencies of 99.85%,illJ While the increase in efficiency is small, when applied to large heavily- loaded transformers the annual savings in energy losses is significant. A small transformer, such as a plug-in .".wall::-JX.<.:t-.l1'' orpower ad,N11Qf type used for low- power consumer electronics, may be no more than 85% efficient, with considerable loss even when not supplying any load. Though individual power loss is small, the aggregate losses from the very large number of such devices is coming under increased scrutiny.lli.l. The losses vary with load current, and may be expressed as "no-load" or "full-load" loss. Winding resistance dominates load losses, whereas hysteresis and eddy currents losses contribute to over 99% of the no-load loss. The no-load loss can be significant, meaning that even an idle transformer constitutes a drain on an electrical supply, which encourages development oflow-loss transformers (also see energy efficient transformer).illl &J Transformers are among the most efficient of machines, but all exhibit losses Transformer losses are divided into losses in the windings, termed copper loss, and those in the magnetic circuit, termed irOJllos~. Losses in the transformer arise from: Winding resistance Current flowing through the windings causes resistive heating of the conductors. At higher frequencies, ~_kin effect and proximity~ffect create additional winding resistance and losses. Hysteresis losses Each time the magnetic field is reversed, a small amount of energy is lost due to hysteresis within the core. For a given core material, the loss is proportional to the frequency, and is a function ofthe peak flux density to which it is subjected.illl Eddy currents Ferromagnetic materials are also good conductors, and a solid core made from such a material also constitutes a single short-circuited tum throughout its entire length. Eddy currents therefore circulate within the core in a plane normal to the flux, and are responsible for resistive_heatillg of the core material. The eddy current loss is a complex function of the square of supply frequency and inverse square ofthe material thickness.1121 Magnetostriction Circuit breaker From Wikipedia, the free encyclopedia Jump to: navigation, search For other uses, see Circuit breaker (disambiguation). ~ •::.1 r I I ~ &:J A 2 pole miniature circuit breaker A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city. Contents • 1 Origins • 2 Operation • 3 Arc interruption • 4 Short circuit current • 5 Headline text • 6 Types of circuit breaker • 7 Low voltage circuit breakers o 71 Magnetic circuit breaker o 7. 2 Thermomagnetic circuit breaker o 7. 3 Rated circuits o 7.4 Common triQ breakers • 8 Medium-voltage circuit breakers • 9 High-voltage circuitbreaker~ • 10 Sulfur Hexafluoride (SF6) high-voltage cirCLtit-breakers • • • • o 10.1 Brief history o 10.2 Thermal blast chambers o 10.3 Self-blast chambers o 10.4 Double motion of contacts o 10.5 Comparison of single motion and double motion techniqu~~ o 10.6 Thermal blast chamber with arc-assisted opening o 10.7 Generator circuit-breakers o 10.8 Evolution oftripping energy o 10.9 Future perspectives 1 l Other breakers 12 See also 13 References 14 External links [edit] Origins An early form of circuit breaker was described by Edism::t in an 1879 patent application, although his commercial power distribution system used fuses. ill Its purpose was to protect lighting circuit wiring from accidental short-circuits and overloads. [edit] Operation All circuit breakers have common features in their operation, although details vary substantially depending on the voltage class, current rating and type of the circuit breaker. The circuit breaker must detect a fault condition; in low-voltage circuit breakers this is usually done within the breaker enclosure. Circuit breakers for large currents or high voltages are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism. The trip solenoid that releases the latch is usually energized by a separate battery, although some high-voltage circuit breakers are self-contained with current transformers, protection relays, and an internal control power source. Once a fault is detected, contacts within the circuit breaker must open to interrupt the circuit; some mechanically stored energy within the breaker is used to separate the contacts, although some of the energy required may be obtained from the fault current itself The stored energy may be in the form of springs or compressed air. Small circuit breakers may be manually operated; larger units have solenoids to trip the mechanism, and electric motors to restore energy to the springs. The circuit breaker contacts must carry the load current without excessive heating, and must also withstand the heat of the arc produced when interrupting the circuit. Contacts are made of copper or copper alloys, silver alloys, and other materials. Service life of the contacts is limited by the erosion due to interrupting the arc. Miniature circuit breakers are usually discarded when the contacts are worn, but power circuit breakers and high- voltage circuit breakers have replaceable contacts. When a current is interrupted, an 9crc is generated-this arc must be contained, cooled, and extinguished in a controlled way, so that the gap between the contacts can again withstand the voltage in the circuit. Different circuit breakers use vacuum, air, insulating gas, or oil as the medium in which the arc forms. Different techniques are used to extinguish the arc including: • Lengthening of the arc • Intensive cooling (in jet chambers) • Division into partial arcs • Zero point quenching • Connecting capacitors in parallel with contacts in DC circuits Finally, once the fault condition has been cleared, the contacts must again be closed to restore power to the interrupted circuit. [edit] Arc interruption Miniature low-voltage circuit breakers use air alone to extinguish the arc. Larger ratings \Vill have metal plates or non-metallic arc chutes to divide and cool the arc. Magnetic blowout coils deflect the arc into the arc chute. In larger ratings, oil circuit breakers rely upon vaporization of some of the oil to blast a jet of oil through the arc. ill Gas (usually sulfur hexafluoride) circuit breakers sometimes stretch the arc using a magnetic field, and then rely upon the dielectric strength of the sulfur hexafluoride (SF6) to quench the stretched arc. Vacuum circuit breakers have minimal arcing (as there is nothing to ionize other than the contact material), so the arc quenches when it is stretched a very small amount (<2-3 mm). Vacuum circuit breakers are frequently used in modern medium-voltage switchgear to 35,000 volts. Air circuit breakers may use compressed air to blow out the arc, or alternatively, the contacts are rapidly swung into a small sealed chamber, the escaping of the displaced air thus blowing out the arc. Circuit breakers are usually able to terminate all current very quickly: typically the arc is extinguished between 30 ms and 150 ms after the mechanism has been tripped, depending upon age and construction of the device. [edit] Short circuit current Circuit breakers are rated both by the nonnal current that are expected to carry, and the maximum short-circuit current that they can safely interrupt. Under short-circuit conditions, a current many times greater than nonnal can exist (see maximum prospective short circuit current). When electrical contacts open to interrupt a large current, there is a tendency for an arc to fonn between the opened contacts, which would allow the current to continue. Therefore, circuit breakers must incorporate various features to divide and extinguish the arc. The maximum short-circuit current that a breaker can interrupt is detennined by testing. Application of a breaker in a circuit with a prospective short-circuit current higher than the breaker's interrupting capacity rating may result in failure of the breaker to safely interrupt a fault. In a worst-case scenario the breaker may successfully interrupt the fault, only to explode when reset, injuring the technician. Miniature circuit breakers used to protect control circuits or small appliances may not have sufficient interrupting capacity to use at a panelboard; these circuit breakers are called "supplemental circuit protectors" to distinguish them from distribution-type circuit breakers. [edit] Headline text [edit] Types of circuit breaker fiJ Front panel of a 1250 A air circuit breaker manufactured by ABB. This low voltage power circuit breaker can be withdrawn from its housing for servicing. Trip characteristics are configurable via DIP switches on the front panel. Many different classifications of circuit breakers can be made, based on their features such as voltage class, construction type, interrupting type, and structural features . [edit] Low voltage circuit breakers Q:J Photo of inside of a circuit breaker Low voltage (less than 1000 V Ac) types are common in domestic, commercial and industrial application, include: • MCB (Miniature Circuit Breaker)-rated current not more than 100 A. Trip characteristics normally not adjustable. Thermal or thermal-magnetic operation. Breakers illustrated above are in this category. • MCCB (Moulded Case Circuit Breaker)-rated current up to 1000 A. Thermal or thermal-magnetic operation. Trip current may be adjustable in larger ratings. • Low voltage power circuit breakers can be mounted in multi-tiers in LV switchboards or switchgear cabinets. The characteristics of LV circuit breakers are given by international standards such as IEC 94 7. These circuit breakers are often installed in draw-out enclosures that allow removal and interchange without dismantling the switchgear. Large low-voltage molded case and power circuit breakers may have electrical motor operators, allowing them to be tripped (opened) and closed under remote control. These may form part of an automatic transfer switch system for standby power. Low-voltage circuit breakers are also made for direct-current (DC) applications, for example DC supplied for subway lines. Special breakers are required for direct current bec~use the arc does not have a natural tendency to go out on each half cycle as for alternating current. A direct current circuit breaker will have blow-out coils which generate a magnetic field that rapidly stretches the arc when interrupting direct current. Small circuit breakers are either installed directly in equipment, or are arranged in a breaker panel. The 10 ampere DIN rail-mounted thermal-magnetic miniature circuit breaker is the most common style in modem domestic consumer units and commercial electrical distribution boards throughout Europe. The design includes the following components: 1. Actuator lever -used to manually trip and reset the circuit breaker. Also indicates the status of the circuit breaker (On or Off/tripped). Most breakers are designed so they can still trip even if the lever is held or locked in the "on" position. This is sometimes referred to as "free trip" or "positive trip" operation. 2. Actuator mechanism-forces the contacts together or apart. 3. Contacts -Allow current when touching and break the current when moved apart. 4. Terminals 5. Bimetallic strip , 6. Calibration ~crew-allows the manufacturer to precisely adjust the trip current of the device after assembly. 7. Solenoid 8. Arc divider I extinguisher [edit] Magnetic circuit breaker Magnetic circuit breakers use a solenoid (electromagnet) whose pulling force increases with the current. The circuit breaker contacts are held closed by a latch. As the current in the solenoid increases beyond the rating of the circuit breaker, the solenoid's pull releases the latch which then allows the contacts to open by spring action. Some types of magnetic breakers incorporate a hydraulic time delay feature using a viscous fluid. The core is restrained by a spring until the current exceeds the breaker rating. During an overload, the speed of the solenoid motion is restricted by the fluid. The delay permits brief current surges beyond normal running current for motor starting, energizing equipment, etc. Short circuit currents provide sufficient solenoid force to release the latch regardless of core position thus bypassing the delay feature. Ambient temperature affects the time delay but does not affect the current rating of a magnetic breaker. [edit] Thermomagnetic circuit breaker Thermomagnetic circuit breakers, which are the type found in most distribution boards, incorporate both techniques with the electromagnet responding instantaneously to large surges in current (short circuits) and the bimetallic strip responding to less extreme but longer-term over-current conditions. [edit] Rated circuits Circuit breakers are rated both by the normal current that are expected to carry, and the maximum short-circuit current that they can safely interrupt. Under short-circuit conditions, a current many times greater than normal can exist (see rn?.ximum prospective short circuit current). When electrical contacts open to interrupt a large current, there is a tendency for an arc to form between the opened contacts, which would allow the current to continue. Therefore, circuit breakers must incorporate various features to divide and extinguish the arc. In air-insulated and miniature breakers an arc chute structure consisting (often) of metal plates or ceramic ridges cools the arc, and magnetic blowout coils deflect the arc into the arc chute. Larger circuit breakers such as those used in electrical power distribution may use vacuum, an mert ~ such as sulphur he~(lfluorig~ or have contacts immersed in pil to suppress the arc. The maximum short-circuit current that a breaker can interrupt is determined by testing. Application of a breaker in a circuit with a prospective short-circuit current higher than the breaker's intermpting capacity rating may result in failure of the breaker to safely interrupt a fault. In a worst-case scenario the breaker may successfully interrupt the fault, only to explode when reset, injuring the technician. International Standard IEC 60898-1 and Eur:opean StandarQ EN 60898-1 define the rated current In of a circuit breaker for low voltage distribution applications as the current that the breaker is designed to carry continuously (at an ambient air temperature of30 °C). The commonly-available preferred values for the rated current are 6 A, 10 A, 13 A, 16 A, 20 A, 25 A, 32 A, 40 A, 50 A, 63 A, 80 A and 100 A ill (Renard series, slightly modified to include current limit ofBritish BS 1363 sockets). The circuit breaker is labeled with the rated current in am per~, but without the unit symbol "A". Instead, the ampere figure is preceded by a letter "B 11 , "C" or "D 11 that indicates the instantaneous tripping current, that is the minimum value of current that causes the circuit-breaker to trip without intentional time delay (i.e., in less than 100 ms), expressed in terms of In: :Type Instantaneous tripping current :B above 3 ln up to and including 5 In !C above 5 In up to and including 10 In iD above 10 In up to and including 20 In i z above 8 In up to and including 12 In For the protection ofloads that cause frequent short duration (approximately 400 ms to 2 s) current peaks in normal operation. above 2In up to and including 3 In for periods in the order oftens.ofseconds. For the protection ofloads such as semiconductor devices or measuring circuits usi~!S current transformers. [edit} Common trip breakers SJ Three pole common trip breaker for supplying a three-phase device. This breaker has a 2 A rating When supplying a branch circuit with more than one live conductor, each live conductor must be protected by a breaker pole. To ensure that all live conductors are interrupted when any pole trips, a "common trip" breaker must be used. These may either contain two or three tripping mechanisms within one case, or for small breakers, may externally tie the poles together via their operating handles. Two pole common trip breakers are common on 120/240 volt systems where 240 volt loads (including major appliances or further distribution boards) span the two live wires. Three-pole common trip breakers are typically used to supply three-phase electric power to large motors or further distribution boards. [edit] Medium-voltage circuit breakers Medium-voltage circuit breakers rated between 1 and 72 k V may be assembled into metal-enclosed switchgear line ups for indoor use, or may be individual components installed outdoors in a substation. Air-break circuit breakers replaced oil-filled units for indoor applications, but are now themselves being replaced by vacuum circuit breakers (up to about 35 kV). Like the high voltage circuit breakers described below, these are also operated by current sensing protective relays operated through current transformers . The characteristics of MV breakers are given by international standards such as IEC 62271. Medium-voltage circuit breakers nearly always use separate current sensors and protection relays, instead of relying on built-in thermal or magnetic overcurrent sensors. Medium-voltage circuit breakers can be classified by the medium used to extinguish the arc: • Vacuum circuit breaker-With rated current up to 3000 A, these breakers interrupt the current by creating and extinguishing the arc in a vacuum container. These can only be practically applied for voltages up to about 35,000 V, which corresponds roughly to the medium-voltage range of power systems. Vacuum circuit breakers tend to have longer life expectancies between overhaul than do air circuit breakers. • Air circuit breaker-Rated current up to 10,000 A. Trip characteristics are often fully adjustable including configurable trip thresholds and delays. Usually electronically controlled, though some models are microprocessor controlled via an integral electronic trip unit. Often used for main power distribution in large industrial plant, where the breakers are arranged in draw-out enclosures for ease of maintenance. • SF6 circuit breakers extinguish the arc in a chamber filled with sulfur heaxafluoride gas. Medium-voltage circuit breakers may be connected into the circuit by bolted connections to bus bars or wires, especially in outdoor switchyards. Medium-voltage circuit breakers in switchgear line-ups are often built with draw-out construction, allowing the breaker to . be removed without disturbing the power circuit connections, using a motor-operated or hand-cranked mechanism to separate the breaker from its enclosure. [edit] High-voltage circuit breakers SJ 400kV SF6 circuit breakers Electrical power transmission networks are protected and controlled by high-voltage breakers. The definition of "high voltage" varies but in power transmission work is usually thought to be 72,500 V or higher, according to a recent definition by the International Electrotechnical Commission (IEC). High-voltage breakers are nearly always solenoid-operated, with current sensing protective relays operated through current transformers. In substations the protection relay scheme can be complex, protecting equipment and busses from various types of overload or ground/earth fault. High-voltage breakers are broadly classified by the medium used to extinguish the arc. • Bulk oil • Minimum oil • Air blast • SF!,> Some ofthe manufacturers are ABB, AREVA Cutler-Hammer (Eaton), Siemens, Toshiba and others. Circuit breaker can be classified as "live tank", where the enclosure that contains the breaking mechanism is at line potential, or dead tank with the enclosure at earth potential. High-voltage AC circuit breakers are ro?tinely available with ratings up to 765,000 volts. High-voltage circuit breakers used on transmission systems may be arranged to allow a single pole of a three-phase line to trip, instead of tripping all three poles; for spme classes of faults this improves the system stability and availability. [edit] Sulfur Hexafluoride (SF6) high-voltage circuit- breakers High-voltage circuit-breakers have greatly changed since they were first introduced about 40 years ago, and several interrupting principles have been developed that have contributed successively to a large reduction of the operating energy. These breakers are available for indoor or outdoor applications, the latter being in the form ofbreaker poles housed in ceramic insulators mounted on a structure. Current interruption in a high-voltage circuit-breaker is obtained by separating two contacts in a medium, such as SF6, having excellent dielectric and arc quenching properties. After contact separation, current is carried through an arc and is interrupted when this arc is cooled by a gas blast of sufficient intensity. Gas blast applied on the arc must be able to cool it rapidly so that gas temperature between the contacts is reduced from 20,000 K to less than 2000 Kin a few hundred microseconds, so that it is able to withstand the transient recovery voltage that is applied across the contacts after current interruption. Sulphur hexafluoride is generally used in present high-voltage circuit-breakers (ofrated voltage higher than 52 kV). In the 1980s and 1990s, the pressure necessary to blast the arc was generated mostly by gas heating using arc energy. It is now possible to use low energy spring-loaded mechanisms to drive high-voltage circuit-breakers up to 800 kV. [edit] Briefhistory The first patents on the use of SF 6 as an interrupting medium were filed in Germany in 1938 by Vitaly Grosse (bEG) and independently later in the USA in July 1951 by H.J. Lingal, T.E. Browne and AP. Storm (Westinghouse). The first industrial application of SF 6 for current interruption dates back to 1953. High-voltage 15 kV to 161 kV load switches were developed with a breaking capacity of 600 A. The first high-voltage SF6 circuit-breaker built in 1956 by Westinghouse, could interrupt 5 kA under 115 kV, but it had 6 interrupting chambers in series per pole. In 1957, the puffer-type technique was introduced for SF 6 circuit breakers where the relative movement of a piston and a cylinder linked to the moving part is used to generate the pressure rise necessary to blast the arc via a nozzle made of insulating material (figure 1 ). In this technique, the pressure rise is obtained mainly by gas compression. The first high-voltage SF6 circuit-breaker with a high short -circuit current capability was produced by Westinghouse in 195 9. This dead tank circuit-breaker could interrupt 41.8 kA under 138 kV (10,000 MV·A) and 37.6 kA under 230 kV (15,000 MV·A). This performance were already significant, but the three chambers per pole and the high pressure source needed for the blast (1.35 MPa) was a constraint that had to be avoided in subsequent developments. The excellent properties ofSF6lead to the fast extension ofthis technique in the 1970s and to its use for the development of circuit breakers with high interrupting capability, up to 800 kV. The achievement around 1983 ofthe first single-break 245 kV and the corresponding 420kV to 550 kV and 800 kV, with respectively 2, 3, and 4 chambers per pole, lead to the dominance of SF 6 circuit breakers in the complete range of high voltages. Several characteristics of SF6 circuit breakers can explain ~heir success: • Simplicity of the interrupting chamber which does not need an auxiliary breaking chamber; • Autonomy provided by the puffer technique; • The possibility to obtain the highest performance, up to 63 kA, with a reduced number of interrupting chambers; • Short break time of2 to 2.5 cycles; Chapter 6. Electromechanical equipment voltage control transmission line generator switch ! figure 6.39 outlet transfonner plant transformer 193 T loads :ircuit diagram :r""ll Wikipedia, the free encyclopedia \circuit diagram (also known as an electrical diagram, firing diagram, elementary diagram, or electronic schematic) ; a simplified conventional pictorial representation of an llectrical circuit. It shows the components of the circuit as ;implified standard symbols, and the power and signal :onnections between the devices. Arrangement of the ;omponents interconnections on the diagram does not ;orrespond to their physical locations in the finished device. 2-- '" '' .. The circuit diagram for a 4 bit TTL Jnlike a block diagram or layout diagram, a circuit diagram counter, a type of state machine ;haws the actual wire connections being used. The diagram joes not show the physical arrangement of components. A jrawing meant to depict what the physical arrangement of the wires and the components they :onnect is called "artwork" or "layout" or the "physical design." Circuit diagrams are used for the design (circuit design), construction (such as PCB layout), and :naintenance of electrical and electronic equipment. Contents . 1 Legends • 2 Symbols • 2. 1 Standards • 2.2 Linkages • 3 European and Australian codes • 4 Organization of drawings • 5 Art Work • 6 See also • 7 External links Legends On a circuit diagram, the symbols for components are labelled with a descriptor (or reference designator) matching that on the list of parts. For example, C 1 is the first capacitor, L 1 is the first inductor, Q1 is the first transistor, and R1 is the first resistor (note that this is not written as a subscript, as in R 1 , L 1 , ... ). The letters that precede the numbers were chosen in the early days of the electrical industry, even before the vacuum tube (then:nionic valve), so "Q" was the only one available for semiconductor devices in the mid-twentieth century. Often the value or type designation of the component is gi• ·-.,on the diagram beside the part, but detailed specifications w~.... _,d go on the parts list. -ll-(..,p.,r:itor Jnn. lnduc:to1 -"NY-fk,i,;l<:: -lf-:'-DC ''olt"g" source t:::"'. .A.C volta<;~~ \.....:';? !iOUf(C ::[:)-f.,•)(l (Jo...;,t~ ~ Nandg~tr: ~ (j((Ji\t-i! p-~~c-·· <J<"e :)I:>-Xo· lf>tc Common circuit diagram symbols (with US Resistor Symbol) ftle://E:\Circuit%20diagram%20-%20Wikipedia, %20the%20free%20encyclopedia.htm 10/2/2008 lrCUlt 01agram -VVIKipeOia, me Tree er IGYGIUfJ~Uid ' """'~---·- ;ymbols :' .-.. diagram symbols have differed from country to country and have changed over time, but are Ovv • ..J a large extent internationally standardized. Simple components often had symbols intended to 3present some feature of the physical construction of the device. For example, the symbol for a 3sistor shown here dates back to the days when that component was made from a long piece of wire trapped in such a manner as to not produce inductance, which would have made it a coil. These 1irewound resistors are now used only in high-power applications, smaller resistors being cast from :arbon composition (a mixture of carbon and filler) or fabricated as an insulating tube or chip coated iith a metal film. The internationally standardized symbol for a resistor is therefore now simplified to 1n oblong, sometimes with the value' in ohms written inside, instead of the zig-zag symbol. A less :ammon symbol is simply a series of peaks on one side of the line representing the conductor, rather han back-and-forth as shown here. )tandards fhere are several national and international standards for graphical symbols in circuit diagrams, in )articular: • IEC 60617 (also known as British Standard BS 3939) • ANSI standard Y32 (also known as IEEE Std 315) IEC 60617 originally consisted of 13 parts, from resistors and capacitors to logic symbols and even a ;:J -1lised drawing standard of connections and bus line widths. It is now published as a subscription online database IEC 60617-DB [1] (http://std.iec.ch/iec60617). Different symbols may be used depending on the discipline using the drawing; for example, lighting and power symbols used as part of architectural drawings may be different from symbols for devices used in electronics. Linkages The linkages between leads were once simple crossings of lines; one wire insulated from and '1umping over'' another was indicated by it making a little semicircle over the other line. With the arrival of computerized drafting, a connection of two intersecting wires was shown by a crossing with a dot or "blob''; c;~nd a crossover of insulated wires by a simple crossing without a dot. However, there was a danger of confusing these two representation~ if the dot was drawn too small or omitted. Modern practice is to avoid using the "crossover with dot" symbol, and to draw the wires meeting at two points instead of one. It is also common to use a hybrid style, showing connections as a cross with a dot while insulated crossings use the semicircle. European and Australian codes To comply with Wikipedia's quality standards, this section may need to be rewritten. file://E:\Circuit 0A)20diagram%20-%20Wikipedia, %2othe%20free%20encyclopedia.htm 10/2/2008 tiiVUI'-"'""'lllo..A~I-111 • •••"''f""--'-1 .,. ·-'' ---· •-.J -·-r----- 3a + + + Schematic wire junctions: 1. Old style: (a) connection, (b) no connection. 2. One CAD style: (a) connection, (b) no connection. 3. Alternative CAD Style: (a) connection, (b) no connection. Please help improve this article (http://en.wikipedia.org/w!index.php? title=Circuit_diagram&action=edit). The discussion page may contain suggestions. The following codes which vary slightly from the American codes are in common use in European and Australian standard electrical circuit diagrams. These codes are used for the "reference designators" printed on PCBs (which match the corresponding ones written on the corresponding schematic). • A: Assemblies • 8: Transducers (photo cells, inductive proximity, thermocouple, flame detection) • C: Capacitors • D: Storage devices • E: Miscellaneous • F: Fuses • G: Generator, battery pack • H: Indicators, lamps (not for illumination), signalling devices • K: Relays, contactors • L: Inductors and filters • M: Motors • N: Analogue devices • P: Measuring/test equipment • Q: Circuit breakers, isolators, re-closers • R: Resistors, brake resistors • S: Switches, push buttons, emergency stops and limit switches • T: Transformers U: Power converters, variable speed drives, soft starters, DC power supplies ~ V: Semiconductors • W: Wires, conductors, power, neutral and earthing busses file://E:\Circuit%20diagram%20-%20Wikipedia, %20the%20free%20encyclopedia.htm 10/2/2008 - ;1rcu1t CJ1agram -WJkJpeCJJa, tne tree encyc1opea1a t"age .q or o • X: Terminal strips, tenninations, joins • Y: Solenoids, electrical actuators • Z: Filters ). ;d rules for reference designations are provided in the International standard IEC 61346. )rganization of drawings tis a usual although not universal convention that schematic drawings are organized on the page rom left to right and top to bottom in the same sequence as the flow of the main signal or power path. =or example, a schematic for a radio receiver might start with the antenna input at the left of the page md end with the loudspeaker at the right. Positive power supply connections for each stage would be ;hown towards the top of the page, with grounds, negative supplies, or other return paths towards the >attorn. Schematic drawings intended for maintenance may have the principle signal paths lighlighted to assist in understanding the signal flow through the circuit. More complex devices have nulti-page schematics and must rely on cross-reference symbols to show the flow of signals between he different sheets of the drawing. Jetailed rules for the preparation of circuit diagrams (and other document kinds used in !lectrotechnology) are provided in the International standard IEC 61082-1. ~elay logic line diagrams (also called ladder logic diagrams) use another common standardized :onvention for organizing schematic drawings, with a vertical power supply "rail" on the left and :mother on the right, and components strung between them like the rungs of a ladder. ~.rwork Once the schematic has been made, it is converted into a layout that :an be fabricated onto a Printed Circuit Board (PCB). The layout is usually prepared by the process of schematic capture. The result is Nhat is known as a Rat's Nest. The Rat's Nest is a jumble of wires (lines) criss crossing each other to their destination nodes. These wires are routed either manually or by the use of Electronics Design Automation (EDA) tools. The EDA tools arrange and rearrange the placement of components and finds paths for tracks to connect various nodes. This results into an Art Work. A generalized design flow would be as: Schematic ~ Schematic Capture ~ Rat's Nest ~ Routing ~ Art Work ~ PCB Development & etching ~ Component Mounting ~ Testing See also A Rat's Nest • AutoTRAX EDA a multiplatform schematic capture, SPICE simulator r;:;;;;------------·, and PCB designer. \I& Electronics portal l ~cad a GPL-ed EDA-Tool used for schematic circuit and PCB design. ·---------·-----------------' gEDA, a GNU EDA-Tool used for schematic circuit design . • Schematic capture file://E :\Circuit%20diagram %20-%20Wikipedia, %20the%20free%20encyclopedia. htm 1 0/2/2008 t'tVI 1,...1'...,,. __ • ....... ,,.,__,._ .. ~~··-~-- \NSI Device Numbers r--ll Wikipedia, the free encyclopedia he ANSI Standard Device Numbersl1J [21 (31 denote what features a protective device supports ;uch as a relay or circuit breaker). These types of devices protect electrical systems and omponents from damage when an unwanted event occurs, such as an electrical fault. .ist of Device Numbers • 1 -Master Element • 2 -Time Delay Starting or Closing Relay • 3 -Checking or Interlocking Relay • 4 -Master Contactor • 5 -Stopping Device • 6 -Starting Circuit Breaker • 7 -Anode Circuit Breaker • 8 -Control Power Disconnecting Device • 9 -Reversing Device • 10 -Unit Sequence Switch • 11 -Reserved for future application • 12 -Overspeed Device • 13 -Synchronous-speed Device • 14 -Underspeed Device 15 -Speed -or Frequency, Matching Device 1 16 -Reserved for future application • 17 -Shunting or Discharge Switch • 18 -Accelerating or Decelerating Device • 19 -Starting to Running Transition Contactor • 20 -Electrically Operated Valve • 21 -Distance Relay • 22 -Equalizer Circuit Breaker • 23-Temperature Control Device • 24-Over-Excitation Relay • 25-Synchronizing or Synchronism-Check Device • 26 -Apparatus Thermal Device • 27 -Undervoltage Relay • 28 -Flame Detector • 29 -Isolating Contactor • 30 -Annunciator Relay • 31 -Separate Excitation Device • 32 -Directional Power Relay • 33 -Position Switch • 34 -Master Sequence Device • 35 -Brush-Operating or Slip-Ring Short-Circuiting, Device • 36 -Polarity or Polarizing Voltage Devices • 37 -Undercurrent or Underpower Relay . 38 -Bearing Protective Device 39 -Mechanical Conduction Monitor • 40 -Field Relay file://E:\ANS I %20Device%20Num bers%20-%20Wikipedia, %20the%20free%20encyclop... 1 0/2/2008 ~~~ uev1ce Nurnoers-VVIKif .. H:.!Uid, u1e 11 c-c-c-''""Y""'vl-'o""''"' • 41 -Field Circuit Breaker • 42 -Running Circuit Breaker • 43 -Manual Transfer or Selector Device -~-Unit Sequence Starting Relay > -Atmospheric Condition Monitor • .<t6-Reverse-phase or Phase-Balance Current Relay • 47-Phase-Sequence Voltage Relay • 48 -Incomplete Sequence Relay • 49-Machine or Transformer, Thermal Relay • 50 -Instantaneous Overcurrent or Rate of Rise, Relay • 51 -AC Time Overcurrent Relay • 52 -AC Circuit Breaker • 53 -Exciter or DC Generator Relay • 54 -High-Speed DC Circuit Breaker • 55 -Power Factor Relay • 56 -Field Application Relay • 57-Short-Circuiting or Grounding (Earthing) Device • 58-Rectification Failure Relay • 59 -Overvoltage Relay • 60 -Voltage or Current Balance Relay • 61 -Machine Split Phase Current Balance • 62 -Time-Delay Stopping or Opening Relay • 63 -Pressure Switch • 64 -Ground (Earth) Detector Relay • 65 -Governor • 66 -Notching or Jogging Device 67 -AC Directional Overcurrent Relay --'8 -Blocking Relay • o9 -Permissive Control Device • 70 -Rheostat • 71 -Level Switch • 72 -DC Circuit Breaker • 73 -Load-Resistor Contactor • 7 4 -Alarm Relay • 75 -Position Changing Mechanism • 76 -DC Overcurrent Relay • 77 -Pulse Transmitter • 78-Phase-Angle Measuring or Out-of-Step Protective Relay • 79 -AC Reclosing Relay • 80 -Flow Switch • 81 -Frequency Relay • 82 -DC Reclosing Relay • 83-Automatic Selective Control or Transfer Relay • 84 -Operating Mechanism • 85 -Carrier or Pilot-Wire Receiver Relay • 86 -Lockout Relay • 87 -Differential Protective Relay • 88 -Auxiliary Motor or Motor Generator • 89 -Line Switch 90 -Regulating Device '·-'31 -Voltage Directional Relay • 92-Voltage and Power Directional Relay file://E:\ANS I%20Device%20Num bers%20-%20Wikipedia, %20the%20free%20encyclop... 1 0/2/2008 '""'' .....,"""""' .. 1--... _..~··--·--·-·- • 93-Field Changing Contactor • 94 -Tripping or Trip-Free Relay • 95-Reluctance Torque Synchrocheck .. .96 -Autoloading Relay 97 -For specific applications where other numbers are not suitable • 98 -For specific applications where other numbers are not suitable • 99 -For specific applications where other numbers are not suitable tote 1 : A suffix letter may be used with the device number; for example, suffix N is used if the device i connected to a Neutral wire (example: 59N in Siemens Relay is used for protection against Neutral lisplacement); and suffixes X,Y,Z are used for auxiliary devices. Similarly, the "G" suffix denotes a ~round", hence a "51 G" being a time overcurrent ground relayl41. lote 2: A suffix number may also be used with a device number: numbers are used to distinguish 1ultiple "same" devices in the same equipment such as 51-1, 51-2. Jote 3: Device numbers may be combined if the device provides multiple functions, such as the 1stantaneous/time-delay AC over current relay denoted as 50/51 ~ote 4: For function descriptions, refer to IEEE standards reference library or American Standards ~37. For understanding and learning application of these devices, many technical reference books 1ave been published and are are available. These device numbers and their application are typically n the domain of electrical engineers, specifically power generation, transmission or distribution ;ystem engineers in regards to safely controlling and protecting users and equipment 5] References 1. A GE Multilin -ANSI Standard Device Number (http://www.geindustrial.com/pm/notes/ref/ANSI.pdf) 2. A Protective Relaying Manual, Pennsylvania Electric Association (1975) 3. /1. Basler Electric-ANSI/IEEE Device Numbers (http://www.basler.com/downloads/ANSI_functions.pdf) 4. A GE Power Management -Relay Selection Guide (http://www.geindustrial.com/pm/notes/get8048a.pdf) 5. A Notes 2, 3 & 4: Applied Protective Relaying 1979 by Westinghouse Electric Corporation, 2nd Printing, "Appendix II, Electrical Power System Device Numbers and Functions" as adopted by IEEE standard and incorporated in American Standard C37.2-1970. Retrieved from "http://en.wikipedia.org/wiki/ANSI_Device_Numbers" Categories: Electronics terms • This page was last modified on 12 September 2008, at 17:23. • All text is available under the terms of the GNU Free Documentation License. (See Copyrights for details.) · Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a U.S. registered 501 (c)(3) tax-deductible nonprofit char~ty. file: /IE: \ANSI %20Device%20Numbers %20-%20Wikipedia, %20the%20free%20encyclop... 1 0/2/2008 Pelton wheel From Wikipedia, the free encyclopedia .5J Pelton wheel from Walchensee, Germany hydro power station ~ Figure from Pelton's original patent (October 1880) OJ Figure from Pelton's original patent (October 1880) 6J Plari view of a Pelton turbine installation (courtesy Voith Siemens Hydro Power Generation). The Pelton wheel is among the most efficient types of water turbines. It was invented by Lester Allan Pelton (1829-1908) in the 1870s, and is an impulse machine, meaning that it uses the principle ofNewton's second law to extract energy from a jet of fluid. Although the one-piece cast impulse water turbine was invented by Samuel Knight in Sutter Creek, in the Cali(ornia ]yfother Lode gold mining region, Pelton modified this invention to create his more efficient design. l(nrght Foundry is the last water-powered foundry known to exist in the United States and is still operated using Knight impulse turbines, used to extract power from high heads /low discharge water flows. Contents • l Function • Z.Applications • 3 Design Rules o 3.1 Imperia!Units o 3 .2 Metric Units • 4 Turbine Physics and Derivation o 4.1 Energy and Initial Jet Velocitv o 4.2 Final Jet Velocity o 4.3 Optimal Wh~elSpeed o :t.1.J o rq u~ o 4.5 Power o 4.6 Efficiencv • 5 Examples and Design Data • 6 Svstem components • 7 Additional physic~ information • ~~e also • 2. R~fert::nces • l9~xternal links [edit] Function The water flows along the tangent to the path of the runner. Nozzles direct forceful streams of water against a series of spoon-shaped buckets mounted around the edge of a wheel. As water flows into the bucket, the direction of the water velocity changes to follow the contour of the bucket. When the water-jet contacts the bucket, the water exerts pressure on the bucket and the water is decelerated as it does a "u-turn" and flows out the other side of the bucket at low velocity. In the process, the water's momentum is transferred to the turbine. This "impulse" does work on the turbine. For maximum power and efficiency, the turbine system is designed such that the water-jet velocity is twice the velocity ofthe bucket. A very small percentage of the water's original h:in~tic energv will still remain in the water; however, this allows the bucket to be emptied at the same rate it is filled, (see consyrvatign of m{!§lt), thus allowing the water flow to continue uninterrupted. Often two buckets are mounted side-by-side, thus splitting the water jet in half(see photo). This balances the side-load forces on the wheel, and helps to ensure smooth, efficient momentum transfer of the fluid jet to the turbine wheel. Because water and most liquids are nearly incompressible, almost all of the available energy is extracted in the first stage of the hydraulic turbine. Therefore, Pelton wheels have only one turbine stage, unlike gas turbines that operate with compressible fluid. [edit] Applications Pelton wheels are the preferred turbine for hydro-power, when the available water source has relatively high hydraulic head at low flow rates. Pelton wheels are made in all sizes. There exist multi-ton Pelton wheels·mounted on vertical oil pad bearings in hydroelectric plants. The largest units can be up to 200 megawatts. The smallest Pelton wheels are only a few inches across, and can be used to tap power from mountain streams having flows of a few gallons per minute. Some of these systems utilize household plumbing fixtures for water delivery. These small units are recommended for use with thirty metres or more of head, in order to generate significant power levels. Depending on water flow and design, Pelton wheels operate best with heads from 15 metres to 1,800 metres, although there is no theoretical limit. The Pelton wheel is most efficient in high head applications (see the "Design Rules" section). Thus, more power can be extracted from a water source with high-pressure and low-flow than from a source with low-pressure and high-flow, even though the two flows theoretically contain the same power. Also a comparable amount of pipe material is required for each of the two sources, one requiring a long thin pipe, and the other a short wide pipe. (edit] Design Rules For a given turbine application, if one knows the water head, desired wheel speed and output power, then the following formula can indicate the appropriate type of turbine. [edit] Imperial Units The "specific speed" is defined as ns n"J'(P)/h 514 • where 'n' is the wheel speed in RPM • P is the power in HP • h is the water head in [edit] Metric Units The "specific speed" is ns = 0.2626 n"J'(P)/h 514 • where 'n' is the wheel speed in RPM • P is the power in kW • h is the water head in meters Well-designed efficient machines typically use the following values: Impulse turbines have the lowest ns values, typically ranging from 1 to 10, a Pelton wheel is typically around 4, francis turbines fall in the range of 10 to 100, while Kaplan turbines are at least 100 or more. Dl The formula suggests that the Pelton turbine is most suitable for applications with relatively high hydraulic head, due to the 5/4 exponent being greater than unity, and given the low characteristic specific speed of the Pelton. [edit] Turbine Physics and Derivation [edit] Energy and Initial Jet Velocity In the ideal (frictionless) case, all of the hydraulic lLQ_tential energy (Ep mgh) is converted into kinetic energy (Ek = mi/2) (see Bernoulli's principle). Equating these two equations and solving for the initial jet velocity (Vi) indicates that the theoretical (maximum) jet velocity is Vi ...J(2gh) . For simplicity, assume that all of the velocity vectors are parallel to each other. Defining the velocity of the wheel runner as: (u), then as the jet approaches the runner, the initial jet velocity relative to the runner is: (Vi-u). UJ [edit] Final Jet Velocity Assuming that the jet velocity is higher than the runner velocity, if the water is not to become backed-up in runner, then due to conservation of mass, the mass entering the runner must equal the mass leaving the runner. The fluid is assumed to be incompressible (an accurate assumption for most liquids). Also it is assumed that the cross-sectional area of the jet is constant. All of this means that the jet speed remains constant relative to the runner. So as the jet recedes from the runner, the jet velocity relative to the runner is: -(Vi -u) -Vi+ u. In the standard reference frame (relative to the earth), the final velocity is then: Vr (-Vi+ u) + u -Vi+ 2u [edit] Optimal Wheel Speed We know that the ideal runner speed will cause all of the kinetic energy in the jet to be transferred to the wheeL In this case the final jet velocity must be zero. If we let -Vi + 2u = 0, then the optimal runner speed will be u Vi 12, or half the initial jet velocity. [edit] Torque By newton's second and third law:;, the force F imposed by the jet on the runner is equal but opposite to the impulse or rate of momentum change ofthe fluid, so: F = -(m)( Vr-Vi)= -(pQ)[(-Vi + 2u)-Vi] -(pQ)[(-2Vi + 2u)] = 2pQ(Vi-u) where (p) is the density and (Q) is the volume rate of flow of fluid. If(D) is the wheel diameter, the torque on the runner is: T = F(D/2) pQD(Vi-u). The torque is at a maximum when the runner is stopped (i.e. when u = 0, T = pQDV1 ). When the speed of the runner is equal to the initial jet velocity, the torque is zero (i.e. when u=Vi, then T=O). On a plot of torque versus runner speed, the torque curve is straight between these two points [(0, pQDVi) and (V1, O)].ill [edit) Power The power P = Fu = Tro, where w is the angular velocity of the wheel. Substituting for F, we have P = 2pQ(Vi-u)u. To find the runner speed at maximum power, take the derivative ofP with respect to u and set it equal to zero, [dP/du = 2pQ(Vi-2u)]. Maximum power occurs when u = Vi /2. Pmax = pQVi2 /2. Substituting the initial jet power Vi --.1(2gh), this simplifies to Pmax = pghQ. This quantity exactly equals the kinetic power of the jet, so in this ideal case, the efficiency is 100%, since all the energy in the jet is converted to shaft output. ill [!dit] Efficiency The wheel power divided by the initial jet power, is the turbine efficiency, 11 = 4u(Vi - u)N?. It is zero for u 0 and for u =Vi. As the equations indicate, when a real Pelton wheel is working close to maximum efficiency, the fluid flows off the wheel with very little residual velocity. ill Apparently, this basic theory does not suggest that efficiency will vary with hydraulic head, and further theory is required to show this. l.edit] Examples and Design Data A working Pelton wheel was used to generate electricity in Southern California. The system had the following specifications. Pitch diameter, 162" (2.06 m); operatin~ speed, 250 rpm (26.18 rad/s); head, 2200' (670.6 m). The theoretical jet velocity Vi= --J(2gh), is •:::alculated to be 114.6 m/s, and the wheel edge speed u = 53.86 mls. Because u-Vi /2, this data is consistent with the theoretical model. The ratio of the runner velocity u to the ideal jet velocity "'(2gh) is usually denoted q>. As the theoretical model suggests, for a Pelton wheel working at maximum efficiency, q> is about 112. This wheel is estimated to 3 ill have produced about 60,000 HP (45 MW) on a flow of about 7 m /s. · [edit] System components The conduit bringing high-pressure water to the impulse wheel is called the ''penstock". Originally the penstock was the name of the valve, but the te~ has been extended to include all of the fluid supply hydraulics. Penstock is now used as a general term for a water passage and control that is under pressure, whether it supplies an impulse turbine or not. ill [edit] Additional physics information The power potential is the product of the water head and the volume flow rate. Power can be expressed as Power= Force * velocity (where Power is measured in watt§., Force is in newtons, and velocity is measured in metres per second). In the instance of fluid, force is typically reframed as the product of pressure difference and cross-sectional area, (F=P* A). Also, the product of cross-sectional area and average velocity, equals the volume flow rate. Thus the flow-power can be rewritten as P=kp(V/t) (where k is a constant representing the efficiency, p is the pressure difference, and V It is the volume flow rate, or the volume of fluid flow per unit time). So the power, P, is directly proportional to both the pressure difference, and the flow rate. [edit] See also • Hydroelectricity • Hydrogower • Turbine • Water turbine • Frgpcis UJrbine • Kaglan turbine [edit] References 1. 1\!! t!. £4 'li ~.: Technicet!dcrivatwn of basic impulse turbine phvsics bv J .C:llvert [edit] External links Wikimedia Commons has media related to: Pelton wltee/ • Exampj~Hydro at Dorado Vista ranch • Skeg ]).esign Co Retrieved from "l:ill.J2:1/en.wikig~dia.org/wiki/Pelton whe~l" Categories: Tuibines Hidden categories: AUartides_vvith unsourced statements I Articles with unsourced statements since May 2008 Views Turgo turbine From Wikipedia, the free encyclopedia QJ Turgo turbine and generator The Turgo turbine is an impulse water turbine designed for medium head applications . Operational Turgo Turbines achieve efficiencies of about 87%. In factory and lab tests Turgo Turbines perform with efficiencies ofup to 90%. Developed in 1919 by Gilkes as a modification of the Pelton wheel, the Turgo has some advantages over Francis and Pelton designs for certain applications. First, the runner is less expensive to make than a Pelton wheel. Second, it doesn't need an airtight housing like the Francis. Third, it has higher specific speed and can handle a greater flow than the same diameter Pelton wheel, leading to reduced generator and installation cost. Turgos operate in a head range where the Francis and Pelton overlap . While many large Turgo installations exist, they are also popular for small hydro where low cost is very important. Like all turbines with nozzles, blockage by debris must be prevented for effective operation. [edit] Theory of operation The Turgo turbine is an impulse type turbine; water does not change pressure as it moves through the turbine blades. The water's potential energy is converted to kinetic energy with a nozzle. The high speed water jet is then directed on the turbine blades which deflect and reverse the flow. The resulting impulse spins the turbine runner, imparting .,. .4> energy to the turbine shaft. Water exits with very little energy. Turgo runners may have an efficiency of over 90%. A Turgo runner looks like a Pelton runner split in half For the same power, the Turgo runner is one half the diameter of the Pelton runner, and so twice the specific speed. The Turgo can handle a greater water flow than the Pelton because exiting water doesn't interfere with adjacent buckets. The specific speed of Turgo runners is between the Francis and Pelton. Single or multiple nozzles can be used. Increasing the number of jets increases the specific speed of the runner by the square root of the number of jets (four jets yield twice the specific speed of one jet on the same turbine ). [edit] See also • ~Y~ter tllr:b.iJl~ • Hydroelectrtc_JlQ~ver [edit] External links • I unw turbine math Czecl1 • Gilkes turgo.JJJrbines • ,C:::ommercial smatlturgo products • \VK \~ T!J.[gQ turbines Retrieved from "http// en. wiki pedia om/wiki/:LtJI.g9 _ turb.ir1s:" ="''="""·'-=· = I\t_[Qines I HyQfQ~Iectri<::it,y Views • Article • Discus5i0J1 • EdiLthis page • Histot:y Personal tools • Log in/ create account Navigation • Mainpag~ • Content~ • E~Jllured.~QJltGnt Francis turbine From Wikipedia, the free encyclopedia Francis turbine (courtesy Voith-Siemens) The: Francis turbine is a type of water turbine that was developed by James B. Francis.It is an inward flow reactioQ turbin~ that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today. They operate in a head range of ten meters to several hundred meters and are primarily used for electrical power production. Contents • 1 Development • 2 Theory of operation • 3 Application • 4 See also. • 5 External links (edit] Development l -~--............. ~·· . ......-··· .. . ! ' - OJ Francis Runner, Grand Coulee Dam Water wheels have been used historically to power mills of all types, but they are inefficient. 19th century efficiency improvements of water turbines allowed them to compete with steam engines (wherever water was available). In 1826 Benoit F ourneyron developed a high efficiency (80%) outward flow water turbine. Water was directed tangentially through the turbine runner causing it to spin. Jean-Victor Poncelet designed an inward-flow turbine in about 1820 that used the same principles. S . B . Howd obtained a U .S. patent in 1838 for a similar design. In 1848 James B. F ranci s improved on these designs to create a turbine with 90% efficiency. He applied scientific principles and testing methods to produce the most efficient turbine design ever. More importantly, his mathematical and graphical calculation methods improved the state of the art of turbine design and engineering . His analytical methods allowed confident design of high efficiency turbines to exactly match a site's flow conditions. [edit] Theory of operation bJ Three Gorges Dam Francis Turbine The Francis turbine is a reaction turbine, which means that the working fluid changes pressure as it moves through the turbine, giving up its energy. A casement is needed to contain the water flow . The turbine is located between the high pressure water source and the low pressure water exit, usually at the base of a dam. The inlet is spiral shaped. Guide vanes direct the water tangentially to the runner. This radial flow acts on the runner vanes, causing the runner to spin. The guide vanes (or wicket gate) may be adjustable to allow efficient turbine operation for a range of water flow conditions. As the water moves through the runner its spinning radius decreases, further acting on the runner. Imagine swinging a ball on a string around in a circle. If the string is pulled short, the ball spins faster. This property, in addition to the water's pressure, helps inward flow turbines harness water energy. Francis Turbine and generator Guide vanes at minimum flow setting (cut-away view) Guide vanes at full flow setting (cut-away view) At the exit, water acts on cup shaped runner features, leaving with no swirl and very little kinetic or potential energy. The turJ:>ine's exit tube is shaped to help decelerate the water flow and recover the pressure. [edit] Application ·SJ Small swiss-made Francis turbine Large Francis turbines are individually designed for each site to operate at the highest possible efficiency, typically over 90%. Francis type units cover a wide head range, from 20 meters to 700 meters and their output varies from a few kilowatt to 1000 megawatt. In addition to electrical production, they may also be used for pumped storage; where a reservoir is filled by the turbine (acting as a pump) during low power demand, and then reversed and used to generate power during peak demand. Francis turbines may be designed for a wide range of heads and flows. This, along with their high efficiency, has made them the most widely used turbine in the world. [edit] See also • Hydroelectricity • Hydropower • Turbine • Water turbine • Kaplan Turbine • Pelton Turbine [edit] External links Kaplan turbine From Wikipedia, the free encyclopedia 6=1 A Bonneville Dam Kaplan turbine after 61 years of service The Kaplan turbine is a propeller-type water turbine that has adjustable blades. It was developed in 1913 by the Austrian professor Viktor Kaplan. The Kaplan turbine was an evolution of the Francis turbine . Its invention allowed efficient power production in low head applications that was not possible with Francis turbines. Kaplan turbines are now widely used throughout the world in high-flow, low-head power production. Contents • 1 Development • 2 Theory of OQeration • 3 Applications • 4 Variations • S See also • 6 References [edit] Development Viktor Kaplan living in Bmo, Moravia, now Czech Republic, obtained his first patent for an adjustable blade propeller turbine in 1912. But the development of a commercially successful machine would take another decade. Kaplan struggled with cavitation problems, and in 1922 abandoned his research for health reasons. In 1919 Kaplan installed a demonstration unit at Podebrady, Czechoslovakia. In 1922 Voith introduced an 1100 HP (about 800 kW) Kaplan turbine for use mainly on rivers. In 1924 an 8 MW unit went on line at Lilla Edet, Sweden. This marked the commercial success and wide spread acceptance of Kaplan turbines. [edit] Theory of operation &:! Vertical Kaplan Turbine (courtesy Voith-Siemens). The Kaplan turbine is an inward flow reaction turbine, which means that the working fluid changes pressure as it moves through the turbine and gives up its energy. The design combines radial and axial features. The inlet is a scroll-shaped tube that wraps around the turbine's wicket gate. Water is directed tangentially, through the wicket gate, and spirals on to a propeller shaped runner, causing it to spin. The outlet is a specially shaped draft tube that helps decelerate the water and recover kinetic _energy. The turbine does not need to be at the lowest point of water flow, as long as the draft tube remains full of water. A higher turbine location, however, increases the suction that is imparted on the turbine blades by the draft tube. The resulting pressure drop may lead to _9avitation. Variable geometry of the wicket gate and turbine blades allow efficient operation for a range of flow conditions. Kaplan turbine efficiencies are typically over 90%, but may be lower in very low head applications. Current areas of research include CFD driven efficiency improvements and new designs that raise survival rates of fish passing through. Because the propeller blades are rotated by high-pressure hydraulic oil, a critical element of Kaplan design is to maintain a positive seal to prevent emission of oil into the waterway. Discharge of oil into rivers is not permitted. [edit] Applications Kaplan turbines are widely used throughout the world for electrical power production. They cover the lowest head hydro sites and are especially suited for high flow conditions. Inexpensive micro turbines are manufactured for individual power production with as little as two feet ofhead. Large Kaplan turbines are individually designed for each site to operate at the highest possible efficiency, typically over 90%. They are very expensive to design, manufacture and install, but operate for decades. [edit] Variations Wikimedia Commons has media related to: Kaplan turbine The Kaplan turbine is the most widely used of the propeller-type turbines, but several other variations exist: Propeller turbines have non-adjustable propeller vanes. They are used in where the range of head is not large. Commercial products exist for producing several hundred watts from only a few feet of head. Larger propeller turbines produce more than 100 MW. Bulb or Tubular turbines are designed into the water delivery tube. A large bulb is centered in the water pipe which holds the generator, wicket gate and runner. Tubular turbines are a fully axial design, whereas Kaplan turbines have a radial wicket gate. Pit turbines are bulb turbines with a gear box. This allows for a smaller generator and bulb. Straflo turbines are axial turbines with the generator outside of the water channel, connected to the periphery of the runner. ) S-turbines eliminate the need for a bulb housing by placing the generator outside of the water channel. This is accomplished with a jog in the water channel and a shaft connecting the runner and generator. VLH turbine an open flow, very low head "kaplan" turbine slanted at an angle to the water flow. It has a large diameter, is low speed using a permanent magnet alternator with electronic power regulation and is very fish friendly (<5% mortality). VLH Turbine Tyson turbines are a fixed propeller turbine designed to be immersed in a fast flowing river, either permanently anchored in the river bed, or attached to a boat or barge. (.--.... -t .. ,lf_ •. . .... _,...._..._<" ~,. .... _, OJ Vertical Kaplan Turbine (courtsey VERBUND-Austrian Hydro Power). ~.,~ .... , ClaH'a.I.VMtM,.a..f• &..ua..rl 6::1 Horizontal Bulb turbine. ( courtsey VERBUND-Austrian Hydro Power). [edit] See also • Hydroelectricity • HydroQower • Turbine • Water turbine • Fran cis turbine • Pelton turbine Bulb I Pit I S turbines The hydraulic development, design and manufacture of bulb and pit turbines has been significantly influenced by Voith Siemens Hydro Power Generation for decades. The higher full-load efficiency and higher flow capacities of bulb and pit turbines can offer many advantages over vertical Kaplan turbines . In the overall assessment of the project, the application of bulb/pit turbines results in higher annual energy and lower relative construction costs. For heads lower than 10m, pit-type turbines have been applied, with a speed increaser located between the runner and generator. h· · Deutsch ) ) Cross section of a bulb turbine and generator. Jing Nan. China. Q. Runner during balancing test, New Martinsville, USA . --.,-.. , \ ... ;a, ... :t ~ fl it .;.. \· -· .. ~ia!. '\~ ·~~ . Workshop assembly, West Enfield, Since 1955 in excess of 180 machines have been placed into operation all over the world with outputs between 50 kW and nearly 50,000 kW and diameters between 800 mm and 8400 mm. Characteristics: As the bulb turbine represents the type most commonly used for high outputs at lowest heads, the S turbine is frequently favoured for the economic utilisation of small hydropowers for outputs up to about8MW. USA. Application range Q. :-Note for U.S . residents Banki turbine From Wikipedia, the free encyclopedia Jump to: navigation, search /li,"Uf<,) 6. 7 Banki turbine. Image credit; European Communities, Layman's Guidebook (on how to develop a small hydro site) A Crossflow turbine, Banki-Michell turbine, or Ossberger turbine is a water turbine developed by the Australian Anthony Michell, the Hungarian Donat Bfmki and the German Fritz Ossberger. Michell obtained patents for his turbine design in 1903, and the manufacturing company Weymouth made it for many years. Ossberger's first patent was granted in 1922, and he manufactured this turbine as a standard product. Today, the company founded by Ossberger is the leading manufacturer of this type of turbine. Unlike most ~ater turbines, which have axial or radial flows, in a crossflow turbine the water passes through the turbine transversely, or across the turbine blades. As with a waterwheel, the water is admitted at the turbine's edge. After passing the runner, it leaves on the opposite side. Going through the runner twice provides additional efficiency. When the water leaves the runner, it also helps clean the runner of small debris and pollution. The cross-flow turbine is a low-speed machine. Although the illustration shows one nozzle for simplicity, most practical crossflow tmbines have two, arranged so that the water flows do not interfere. Crossflow turbines are often constructed as two turbines of different capacity that share the same shaft. The turbine wheels are the same diameter, but different lengths to handle different volumes at the same pressure. The subdivided wheels are usually built with volumes in ratios of 1:2. The subdivided regulating unit (the guide vane system in the turbine's upstream section) provides flexible operation, with Y3,% or 100% output, depending on the flow. Low operating costs are obtained with the turbine's relatively simple construction. Contents • 1 Details of design • 2 Advantages • 3 See also • 4 External links [edit] Details of design OJ Ossberger turbine section The turbine consists of a cylindrical water wheel or runner with a horizontal shaft, composed of numerous blades (up to 37), arranged radially and tangentially. The blades' edges are sharpened to reduce resistance to the flow of water. A blade is made in a part- circular cross-section (pipe cut over its whole length). The ends of the blades are welded to disks to form a cage like a hamster cage; instead of the bars, the turbine has trough- shaped steel blades . The water flows first from the outside of the turbine to its inside. The regulating unit, shaped like a vane or tongue, varies the cross-section of the flow. The water jet is directed towards the cylindrical runner by a fixed nozzle . The water enters the runner at an angle of about 45 degrees, transmitting some ofthe water's kinetic energy to the active cylindrical blades. &3 Ossberger turbine runner The regulating device controls the flow based on the power needed, and the available water. The ratio is that (0--100%) ofthe water is admitted to O-lOO%x 30/4 blades. Water admission is to the two nozzles is throttled by two shaped guide vanes. These divide and dire<;t the flow so that the water enters the runner smoothly for any width of opening. The guide vanes should seal to the edges of the turbine casing so that when the water is low, they can shut off the water supply. The guide vanes therefore act as the valves between the penstock and turbine. Both guide vanes can be set by control levers, to which an automatic or manual control may be connected. The turbine geometry (nozzle-runner-shaft) assures that the water jet is effective. The water acts on the runner twice, but most of the power is transferred on the first pass, when the water enters the runner. Only Y3 of the power is transferred to the runner when the water is leaving the turbine. The water flows through the blade channels in two directions: outside to inside, and inside to outside. Most turbines are run with two jets, arranged so two water jets in the runner will not affect each other. It is, however, essential that the turbine, head and turbine speed are harmonised. The cross-flow turbine is of the impulse type, so the pressure remains constant at the runner. [edit] Advantages The peak efficiency of a crossflow turbine is somewhat less than a Kaplan, Francis or Pelton turbine. However, the crossflow turbine has a flat efficiency curve under varying load. With a split runner and turbine chamber, the turbine maintains its efficiency while the flow and load vary from l/6 to the maximum. Since it has a low price, and good regulation, crossflow turbines are mostly used in mini and micro hydropower units less than two thousand kW and with heads less than 200m. Particularly with small run-of-the-river plants, the flat efficiency curve yields better armual performance than other turbine systems, as small rivers' water is usually lower in some months. The efficiency of a turbine determine whether electricity is produced during the periods when rivers have low heads. If the turbines used have high peak efficiencies, but behave poorly at partial load, less annual performance is obtained than with turbines that have a flat efficiency curve. Due to its excellent behaviour with partial loads, the crossflow turbine is well-suited to unattended electricity production. Its simple construction makes it easier to maintain than other turbine types; only two bearings must be maintained, and there are only three rotating elements. The mechanical system is simple, so repairs can be performed by local mechanics. Another advantage is that it can often clean itself. As the water leaves the runner, leaves, grass etc. will not remain in the runner, preventing losses. So although the turbine's efficiency is somewhat lower, it is more reliable than other types. No runner cleaning is normally necessary, e.g. by flow inversion or variations of the speed. Other turbine types are clogged easily, and consequently face power losses despite higher nominal efficiencies. [edit] See also • Water turbines [edit] External links Retrieved from "http:iien.wikipedia org/wiki!Banki turb_i_n~" Categories: Im_hines I Hydropower Views • ArticiQ • Di..s£lJ.~~ion • Edit this page • Historv Personal tools • Log in I create_ account Navigation • Main page • Contents • Featured content • Curr_ent events • Random articl~ Search Interaction • About Wikipedia • COJ)1munitv portal • Rece~ · Home Field Service Special Events GovernorSchool2009 Focus Class: Mech Cab Actuators Digital Governor Conversions Mechanical Cabinet Gateshaft Other OEM Governors HMI Systems N Hydraulic Power Units Spare Parts & Support Woodward Mechanical Cabinet Woodward Gateshaft Woodward GS Actuator Woodward A-Actuator IOdward Analog MOD I & II ·oodward Digital Modules & Mise Parts Driver Amplifiers PT Interface Feedback Amplifier Woodward XX Herringbone Gear Pump "oodward 20-Series Rotary Gear Pump IMO Pumps 1»ump Electric Unloader Kits Woodward PMG Services Woodward PMG & Speed Switch Parts P~lton Governor Parts Pelton PMGs On-Site Training Classes Factory Repair Service .!'rr.hurP.~ ;anti RuiiPtin~ Tech Support . Training Upgrades Contact Digital Conversion -Gateshaft Governor Our scope of supply typically includes equipment, engineering and site supervision. Each kit includes a PLC-based digital control cabinet with touchscreen local operator interface, pilot valve electro-hydraulic interface manifold, and electronic speed and gate position sensors. Typical Gateshaft After Conversion The PLC cabinet can be physically mounted and wired by your staff or others using the drawings we provide. During the outage, an experienced Field Service Engineer will be on hand to assist with installation and provide final commissioning and testing services. \ Articles & Papers . Recent Awards Links to Our Vendors Field Service Technical Support Contact Information Careers at AGC ) PLC Governor System The heart of each new governor system will be an Allen-Bradley™ Programmable Logic Controller (PLC). The new controller and accessories will reside in a wall-mount control enclosure that includes the following devices: • Governor PLC (1) 7-slot PLC Rack (1) CPU Module (1) Power Supply Module (1) Contact Input Module -16 channel (1) Contact Output Module -16 channel Typical PLC Governor (1) Analog Input Module -8 channel Cabinet (1) Analog Output Module -4 Shown with front door open channel • Cabinet Power Supply (125VDC/24VDC) • Terminal Blocks (as needed) • Interposing Relays (as needed) Local Operator Interface: Color Touchscreen Mounted on the front door of the PLC Governor, a 6" color +-no ,,.h,.,..,,"'"r'\ Uo ,...,......,. .... M.,.,.h; .... ,.. T ...... ,..~.,.,.,.. fUMY' u•lll ,.,...,..,,.. ..,.,. +-hn • Local Display of Unit Information • System Alarm Display • Input I Output (1/0) Status Display • Event Log • Basic Trending • Access to Tunable Parameters for the Unit • Serial Port for Printing In addition, a door-mounted Emergency Shutdown pushbutton will be provided. .,. •·' • CABin a&J: liiiT B " ""* lit ll OUERlJI EU '"*4'0 ~ fTI Qeoto P'oe t t oon ~ flo•••~ OoH ......... I ... :c! t ... fi1 Sp•.O ~>~•hr....:• I i ii~J L-..-~ C:Of'\t,.OI Mo<Mt !!@ .-i,!E@?f!!§£ I a.,.. 8 reak er ltatua .J ~·.-.-...-:1 o.cr~ ... ,·."I I At-••·'----------......1 .. , .. ' i < ---' :· • ••• -•• :l.i.J.!il . ~ ~ .. ~ ! ·. ~. ~E::!I ---~-~ .. --- Sample Unit Control Screen Cabinet Power Supply A 125VDC/24VDC cabinet power supply will be provided to power the Governor PLC, proportional valve, accessory equipment and field devices . Electro-Hydraulic Interface (EHI) Assembly for Gateshaft Governors The EHI assembly is the basic connection between the PLC Governor and the existing relay valve. The EHI controls the flow of oil to the relay valve, which regulates the flow of oil to the servomot~r to open or close the wicket gates. The assembly includes the fo~lowing devices: ) Proportional Control Valve Enables servomotor control via PLC during normal operation. This high-response valve provides closed-loop control of distributing valve spool position. Solenoid Shutdown Valve Enables emergency shutdown independent of the PLC. When de-energized, the solenoid valve cause.s the distributing valve spool to move fully in the close direction, causing the servomotor to close at the fastest rate allowed by the stop nuts. Hydraulic Manifold A custom manifold for the mounting of valves. Includes shutdown shuttle assembly for independent shutdown via solenoid valve (blocks control flow from proportional valve). Primary Speed Signal Electro-Hydraulic Interface (EHI) Typical Gateshaft configuration shown Primary speed sensing is done via an American Governor Speed Signal Module connected to a generator Potential Transformer. Our high-resolution Speed Signal Module provides one 0-200°/o analog output for metering and one high- resolution analog output for synchronizing and on-line droop control. The module is compliant with IEEE 125 "IEEE Recommended Practice for Preparation of Equipment Specifications for Speed- Governing of Hydraulic Turbines Intended to Drive Electric Generators.'/ Back-up speed sensing is available as an option. Before upgrading Relay Valve Position Feedback (LVDT) The EHI requires an accurate and stable relay valve position signal in order to function closed-loop. A Linear Variable Differential Transformer (LVDT) will be provided for relay valve feedback. Mounting hardware, signal conditioner and connector will be included. EHI Assembly and LVDT Servomotor Position Feedback (MLDT) The Magnetostrictive Linear Displacement Transducer (MLDT) is a superior non-contact alternative to traditional low-cost linear position feedback devices such as linear potentiometers or string pots. An MLDT will be provided for electronic feedback of Wicket Gate servomotor position. Mounting hardware and connector will be included. Gate Feedback MLDT Assemble, Wire & Test American Governor will assemble and wire the complete PLC governor system in Ivyland, PA. Your system will be connected to our Turbine Simulator, which will be programmed to mimic site conditions. All hardware and software will be tested completely before leaving our factory. PLC Control Software American Governor will provide governor control software adapted from proven software algorithms. Typical functionality includes: • Automatic Start I Stop Control • Unit Speed I Frequency Control with Variable Droop • On-Line I Off-Line Gains • Remote On-Line Setpoint from Plant Control • Gate Limit Control • Maintenance-Manual Position Control • Automatic Pre-Load (To Prevent Reverse Power Condition) • Soft Loading & Unloading of Unit • Speed Switches and Gate Position Switches (as required) • System Alarm Indications • IIO and CPU Diagnostics Ill. LICENSING Numerous laws enacted over many years at the 1 oca l , state and federal levels have resulted in a large number of permit and license requirements which must be met before a hydro proje~t can be built. Most projects ~iZZ not require all the permits or approvals listed in this chapter. · Small projects in particular are likely to require very few permits, but this will vary on a case by case basis. It is important for the prospective developer to regard the regulatory requirements not as barriers to be surmounted or circumvented, but as a means to identify potential problems associated with a particular site or project design. Agencies responsible for the permits and licenses should be consulted early in the development process, so that any appropriate modifications to the project can be made in a timely manner. LAND ACCESS Development of any hydropower project requires the developer to secure ownership, leases, easements, rights- of-way, or other approval to occupy and use land at the site and along transmission lines. This right may be obtained by purchase or through permit or easement from property owners. Direct negotiation with private property owners, such as village corporations, native corporations, or individuals is reconnended. Sources for determining land ownership can include: coastal zone management plans; regional compre- hensive plans; timber management plans, and Alaska Power Authority reconnaissance and feasibility reports. These references are usually located in the Alaska State Deposito- ry libraries by subject index {see Appendix 8). Agencies or organizations managing federal and state land in the vicinity of a project should be contacted for additional information, such as: Federal Bureau of Land Management Land Information Office 701 C Street Anchorage, Alaska 99501 Alaska Department of Natural Resources Recorder's Office 3601 C Street, Suite 1134 Anchorage, Alaska 99503 Development on designated parklands and game sanctu- aries is restricted. Parklands include national and state parks, forests, preserves, monuments and wilderness areas. Permission to utilize or cross national parklands ·could require an act of the U.S. Congress. Application for easements must be made through the National Park Service, or the Department of Agriculture, Forest Service. The Alaska Department of Natural Resources manages state parkland. ALASKA PERMITTING PROCEDURES Although it is difficult to rank the environmental acceptability of various types of hydropower configurations in general terms, resource agencies agree that projects involving an existing dam (or, for small projects, no dam at all) have fewer adverse impacts than projects requiring construction of a new dam. Similarly, run-of-river and diversion type projects (assuming maintenance of adequate instream flows for diversion projects) generally are more environmentally acceptable than projects involving a storage reservoir. Examples of possible development impacts include: a reduction of fish in the stream; changes in water quality during construction; disturbance of wildlife; less or no water in the stream between the intake and powerhouse. Permitting processes give agencies a chance to review and comment on a project. It is atso an oppo~tunity for the develope~ to obtain some f~ee technical advice. Since there are many agencies involved, the complete permitting ·process may take 18 months or more for a large project. In some instances compliance with regulations might require .project alterations. If a permit is denied, the project requires reevaluation. State permits pertain to water rights, fish and game, and use of state 1 and. An inventory of State agencies charged with review of hydroelectric projects follows. federal ·Agencies I fElC Preii•I~~~Y P~-t--;;~~-;~~---] FERC Qualified Facility Designation • Optional federal Agencies to Contact In FERC Prellcenalng Proce111 U.S. flah & Wildlife Service Envtron.~ntal Protectton Agency U.S. Corpa of Engineers National Marina Ftaherlea Service Interior Deparblent EnvlronMOnte1 Dlvlalon Other federal Agencies; N•tlonal Perk Service • Perk Landa Federal Avletlon A~lnlatratlon • Tran.-lltfon Linea i ! i ~ ~ ~ ~ De&lre to Develop a Hicrohydro Project ' Reconnalaaance Level Studlea of Natural Featurea and land' Uae/Ownerahlp Completed • Contact Appropriate Agencies for Per•lta and Rlghta·of·Way I I State of A I uka Oepart.ent of Envlron.entel Conaervetfon ·Neater Per•lt Appllcetfon/Stre .. Olach1rge Oepert.ent of Neturel Reaourcea • Water Rights end o .. Construction Oepert.ent of flah & C1.a • Habitat Protection Office of Nanag ... nt & Budget • Co.atal Men•t ... nt Aleaka Public Utlll~les Ca..laalon -Utility Interconnection WATER AND LAND USE REQUIREMENTS Table 8 Local Agencli& or Entitie~ Project Located Agency or In or Affecting: Approval: State Land State DHR Private lend Individual( a) Vl1 hge Native Corporation Regional Native Corporation ' Native federal Bureau Allot.nt of Indian Affairs Wllderneu U.S, Foreat Area Service National Park National Park or Moi!UIIIItnt Service Netlonel U.S. Flah & Wildlife Wild I He Refuge Service National U.S. Foreat forest Service Canada International Joint c~•••lon - Corps of Engineers I l-· ,,, STATE AGENCIES • Department of Environmental Conservation {DEC) Master Permit Application The Alaska Permit Information Centers provide a centra- lized statewide environmental permit information service. Permit Information staff can identify all federal, state and local permits that any specific project is 1 ikely to re- quire. In addition, the Centers can arrange for the appli- cant to meet with permitting agencies to discuss how to fill out the applications. A recently updated Alaska Directory of Permits is also available at the Permit Information Centers. Permit Infor- mation Centers are located at: Juneau 465-2615 Anchorage 279-0254 Fairbanks 452-2340 Collect calls are accepted during business hours. The master permit application serves state agencies with a "notice of intent" for a proposed project. The map report and prospectus prepared in a site reconnaissance are submitted with the application to all state departments and the municipality where the project is located. Jurisdiction or permit requirements are then obtained for the applicant for completion and resubmittal. If public hearings are required, DEC will coordinate the hearing in or near the municipality where the hydro project is proposed. Final decisions will be incorporated into one document and return- ed to the applicant. Certificate of Reasonable Assurance ficat1on Certification of compliance with Alaska Water Quality Standards are regulated through DEC. Any work, construc- tion, discharge or placement of structures within water ways must satisfy Alaska Administrative Code, regulations 18 AAC 65.050 through 18 AAC 70.010. The Division of Environmental Quality is the administering agency and works in coordination with the U.S.Corps of Engineers to assure standards are satisfactorily met. • Department of Natural Resources (DNR) Application for ~later Rights (Fonn 10-102) The Alaska Water Use Act provides the public with a legal method to obtain water use rights. All use of Alaskan stream water is controlled by the Alaska Department of Natural Resources. Permits must be obtained from the Division of. Land and Water Management (DNR) according to procedures described in their "Water User•s Handbook". A water rights permit will provide legal standing against subsequent conflicting uses,. therefore, early application for the permit is recommended. Only after the water is being beneficially used can a Certificate of Appropriation be issued. This is the legal document which conveys water rights. A water right then becomes a property right attached to the legal description of the property. If the land is sold, the water right goes with the land to the new owner unless special arrangements are made through ONR. Applicants for water rights are advised to contact the Division of Land and Water Management for complete details. Application to Construct or Modify a Dam A dam and reservoir may be required at a proposed site to regulate flow, increase head or as a diversion for the intake design. An Application to Construct or Modify a Dam is required by the Department of Natural Resources for dams which are 10 feet or more in height or capable of storing 50 acre-feet or more of water. In general, any dam 10 feet or more in height will require submission of plans as well as specifications, topographic maps of the dam site, and profiles and cross sections of the dam. Detailed hydrologic data, seepage and permeability analysis of the structure, and a stability analysis must be submitted if the structure is in an earth- quake zone. For dams less than 10 feet in height, or for reservoirs of less than 50 acre-feet in storage, no special additional approval is needed other than the granting of a water rights pennit to develop the water source. Plans and specifica- tions, however, will still be required. The purpose of the dam construction and safety regula- tions is twofold. The primary purpose is to maintain an accurate central file system of existing structures as a precaution in the event of emergency situations. The secondary purpose is to ensure a consistent review of dam construction and the application of sound engineering standards in the construction of dams. Land Leases State land leases also are the responsibility of ONR. Leases and other land issues are not likely to be included in the master permit application inventory.· Contact with the Division of Land and Water Management is necessary. • Department Of Fish & Game (DF&G) Habitat Protection Permit The Department of Fish and Game oversees wildlife management and protection. DF&G• s interest in water use development relates to the protection of resident and anadromous fish (sa 1 mon and s tee 1 head) and the effects of water impoundments on game habitat. A Habitat Protection Permit is required where either resident or anadromous fish are identified. Identification of resident species can be researched at Fish and Game offices. Catalogs and atlases document the extent of anadromous fish migration. Management data on resident fish is also available. Fish and Game is also invited by DNR to conment on water use permit applications. Any restriction of water flow where fish are present will likely necessitate a Habitat Protection Permit. • Office of Management and Budget (OMB) Dfvisfon of Governmental Coerdtnatton Coastal Project Questionnaire and Certification of Consistency ·· Section 307 of the U.S. Coastal Zone Management Act of 1972, as amended by 16 USC 1456{c)(3), governs development in coastal areas. It requires applicants for federal land and water use permits in Alaska's coastal areas to provide certification that activities will comply with the standards of the Alaska Coastal Management Program. All potential hydropower developers seeking permits from two or more state agencies or from a federal agency (F.E.R.C. or the Corps) are required to respond to a coastal project questionnaire. Because A1aska 1 s coastal boundries encompass a substantial amount of interior area as well a rev~ew of the Interim Coastal Zone Boundries map of Alaska, ava1lable at the Governmental Coordination offices, is advisable. The need to meet various en vi ronmenta 1 standards in coastal areas will be determined by OMB on the basis of questionnaire responses. Furthermore, additional guidance on other state and federal permitting procedures is avail- able from OMB during the review process. As their name implies, the Division of Governmental Coordination will communicate with other state and federal agencies to facili- tate permit acquisition and responsiveness to coastal zone issues. • Alaska Public Utility Commission (APUC) Cogeneration and Small Power Production Regulations Although Alaska Statutes do not include a state- specific enactment of the federal Public Utilities Regula- tory Pol icy Act (PURPA}., AS 42.05.361 -42.05.441 enables the APUC to regulate certain electric utilities. Article 2 3AAC 50.750 -3AAC 50.820 includes regulations governing the interconnection, purchase and sale of electric power between a utility and a qualifying facility (QF). In keeping with the spirit of the federal PURPA enact- ment., the APUC's guidelines state that " ••• regulations are to encourage cogeneration and small power production by setting out guidelines for the establishment of reason- able, non-discriminatory charges, rates., terms and condi- tions under which interconnection and purchases and sales of electric power will occur •••• " QF certification is obtained from the Federal Energy Regulatory Commission. Application is pertinent only if the benefits available through PURPA are required from a hydro- plant operation. Examples of benefits include: • Exemption from certain utility regulations dealing with revenues, • Certification for tax benefit purposes9 • Requirements that utility interconnection be allowed, • Requirements relating to a utility selling power to a QF. Applications should be made through the Washington, DC office of FERC. An address is contained in the Agency Directory, Appendix D. Power buy-back rates are governed by whether the power so 1 d can be defined as firm or non-firm. Non-firm rates should now be established for all utilities regulated by APUC. These are directly related to the avoided fuel costs that a utility realizes in the purchase of power from a QF. Finn power rates involve a number of considerations related to increased utility plant capacity which might otherwise be required if no alternative sources were being proposed. Purchase rates are subject to negotiation with the utility but ITl.lst meet requirements set forth in APUC's regulations. Up to sixty days can be required for a tariff decision. Disagreements with the utility over its suggest- ed buy-back rates may be appealed through the APUC, provided it is a regulated utility. FEDERAL PERMITS a UCENSING FEDERAL ENERGY REGULATORY COMMISSION (FERC) The Federal Energy Regulatory Commission {FERC) is the primary federal agency responsible for issuing licenses for all non-federal hydroelectric projects under its juris- diction. The purpose of federal 1 icensing is best stated in Section lO(a) of the Federal Power Act which requires the Coll11lission to assure that: "the project ••• will be best adapted to a comprehensive plan for improving or developing a waterway or waterways for the use or benefit of interstate or foreign commerce, for the improvement and utilization of waterpower development, and for other beneficial public uses, including recreational purposes •••• " In more direct ~erms, C?ngress ~anted to ensure that hydropower development 1n any r1ver bas1n would be compatible with the best overall use of the resource. In addition to the Federal Power Act, Congress has enacted a number of other statutes to assure the original intent of the Act and to protect other public interests. Some of these more recent statutes are listed in Table 9. A hydropower project is within the jurisdiction of FERC, and therefore requires a 1icense or an exemption from licensing, if any of the fo1lowing apply: 1. The project is on a navigable waterway, 2. The project will affect interstate corrmerce (i.e., project wi11 be connected to a regiona1 transmission gridL 3. The project uses federal land, 4. The project will use surplus water or waterpower from a federal dam. Under these criteria very few projects are exempt from FERC licensing requirements. Only a very small project which does not affect a navigable waterway or interstate co11111erce and does not hool< up with a grid system would be exempt from FERC involvement. If there is uncertainty regarding FERC jurisdiction, there is a relatively simple legal procedure for obtaining a decision from FERC. A Declaration of Intention is filed according to Part 24 of the FERC regulations (Title 18 CFR). The requirements are short and uncomplicated and can be completed with a minimum of data. A more direct method is to request an unofficial opinion from FERC staff. Preliminary Permit A preliminary permit protects a developer's priority to apply for a license for a particular site and allows further study; it does not authorize construction. FERC permits are broken down into major and minor projects. Microhydro comes under minor projects, less than 1500 kW. The exact specifications for filing a preliminary permit application are in FERC Orders No. 54, 1233, and 183 .and 18 CFR 4.80-4.83. An application consists of an ini- tial statement and four exhibits: , 1. A description of the facility and proposed mode of operation, 2. A map of the general location, 3. An environmental report, 4. A set of drawings showing the existing and proposed project works. Leaislation Table 9 Federal Regulatory Acts Affecting Hydro Development Federal Power Act National Environmental Policy Act Fish and Wildlife Coordination Act Historic Preservation Act Wilderness Act Clean Water Act Wild and Scenic Rivers Act Endangered Species Act Coastal Zone Management Act Federal land Policy & Management Act Public Utilities Regulatory Policies Act Licenses and Exemptions Regulation 16 usc 791 42 usc 4321 16 usc 661 16 usc 470 16 usc 1131 33 usc 1251 16 usc 1271 16 usc 1531 16 usc 1451 43 usc 1701 Pl 95-619 A project which satisfies certain requirements may qua 1 i fy for an exemption from the FERC 1 i cens i ng process. FERC has created two categories of case-specific exemptions and one generic category. Presently, the generic category has been stayed by court order pending further evaluation. The case-specific exemption categories are: 1. Projects less than 15 MW that are built into conduits or provide direct discharge of water for agricultural, municipal or industrial use. 2. Certain projects not exceeding 5 MW which involve dams built prior to 1977 or run-of-river projects which utilize natural water features without the need of an impoundment. If exempted from licensing, a project is not subject to a number of provisions applicable under the Federal Power Act. If the project is located only on federal lands, any person may apply for an exemption. If any part or all of the project is not on federal lands, only the owner of those proper~y interests or the holder of an option to obtain those 1nterests may apply for a exemption. A potential hydro developer is required to consult with local~ state~, and federal agencies (see Table 10) during preparation of a license or exemption application, and include evidence of these consultations in the application. Although the Federal Power Act requires evidence of com- pliance with state and local requirements prior to issuance of a license, FERC may override state and local decisions. FERC issues licenses to construct and operate hydro- electric projects up to 50 years. Projects must be, reli- censed when a previous license expires. For more informa- tion on the FERC 1 icensing and exemption processes, see Appendix 0. FERC's "Bluebook" and FERC Order No. 106 as amended and clarified by Order No. 106-A, and Orders No. 202, 202-B, and 202-C. Recent changes in FERC licensing requirements are outlined in FERC Order No. 189. "Application for License for Minor Water Power Projects and Major Water Projects 5 Megawatts or Less." Table 10 Federal Agency Contacts Required by FERC U.S. Fish and Wildlife Service Environmental Protection Agency U.S. Army Corps of Engineers National Marine Fisheries Service U.S. Department of Interior, Environmental Division NATIONAL ENVIRONMENTAL POLICY ACT (NEPA) Federal agencies making decisions on hydroelectric project licenses are required to comply with the National Envi ronmenta 1 Po 1 ky Act for minor projects and for add i- tions of hydroelectric facilities at existing 4ams. A developer is initially required only to provide enough environmental information for FERC to make a determination of environmental significance. If the project is determined to be environmental~y significant, a full Environmental Impact Statement {EIS) 1s required. When a full NEPA EIS is required. it is written by the FERC staff using the information provided in Exhibit E of the license application. When necessary, FERC wi 11 require that additiona 1 studies and information be provided. FERC regulations regarding NEPA are listed in 18 CFR 2.80-2.82. . OTHER FEDERAL PERMITS • U.S. Army Corps of Engineers Section 10 and Section 404 Permits The Corps of Engineers has jurisdiction over any project which is proposed for a navigable waterway (Sec- tion 10, River and Harbor Act of 1899). or which involves the discharge of any dredge or fill material into waters of the United States (Section 404, Federal Water Pollution Control Act). In general, the Corps does not require a separate Section 10 permit in cases where FERC exercises licensing jurisdiction. The Corps does, however, review and coment on FERC applications as part of FERC 1 s prelicense consulta- tion process to ensure the protection of navigational interests. For projects involving the discharge of dredged or fill material into U.S waters a 404 permit fs required in addi- tion to any FERC action. These applications are made on a general form and take approximately three to six months for approval. Required is information on the nature and location of the proposed activity; the time span involved; and the status of other federal, state, and local permits. The developer should contact the Corps District Engi- neer well in advance of construction. The Corps, Alaska Department of Environmental Conservation and the Division of Governmental Coordination (OMB) work together to ensure that compliance to water quality standards is reviewed and met. The Alaska District Office in Anchorage has jurisdiction over Corps permits within the state. See Appendix D for the address and telephone number. • Federal Aviation Administration (FAA) Determination of No Hazard The FAA has forms which must be completed and reviewed to determine if any project feature (e.g., transmission towers) constitutes a hazard to aviation. A project layout showing elevation contours should be turned in with the application, and inf9rmation on microwave tower and existing airports in the project area may be required. Approval of this permit will take approximately two months. • U.S. Forest Service (USFS) Special Use Permit If any part of a project is on National Forest lands, a Special Use Permit (SUP) is required from the U.S. Forest Service. In order to secure a SUP, the developer must have a FERC license or exemption. The developer then applies to USFS for a Study Special Use Permit (SSUP). This SSUP is for studies which gather information required under NEPA. After NEPA regulations have been satisfied, the USFS writes a 4(e) report, which is their official position toward the project. The 4(e) report is required by FERC as part of its licensing requirements. After FERC has issued a license or exemption. the developer can apply for a SUP in order to begin actual construction. The USFS SUP process can be quite complex and hydropower developers should establish early contact with the Forest Service. 500,000 :,000 300,000 200,000 500 100.000 250 200 ' 70,000 15!1'-' so.ooo ' 100 ' ' 75 ' 30,000 50 -200 20,000 , ' c ' 0 -u 100 ' -CD CD ' --25 en '&-t CD ::I '•~>~.ol. CD c 10,000 ... 50 LL ~ 20 CD ' . -Q. ' 0 ... 7000 -' 30 <I( CD 15 CD ' w Q. CD 5000 LL 20 ' 25 :X: Ctl 10 -' c u ., ' w .2 -...J :a 10 -' £D -• 20 «< 7.5 ::I < ~ 3000 0 I _, --~ -;= 5 ~ 5.0 -< 2000 ~ 15 > 0 4 0 -< _, _, a: LL LL ...J 3 w < ;= ~ 2.0 ~ .... 0 1000 0 0 10 0 ...J 2 _, G. .... 700 1.0 1.5 500 LO 0.5 NOMOGRAPH TO COMPUTE 300 o.z ENERGY POTENTIAL • 5 200 0.1 Plot flow on left and head on right. A line drawn connecting the two will show Potential 100 Energy Production. 0.2 .~. I. 5 Nomographs (scaled charts which can solve for unknown variables when at least two are known) also can be used to demonstrate this relationship. In the nomograph on page 18, an efficiency level has been factored into the equation to account for pipe and machinery losses. Assuming head and flow measurments are known, to use the graph locate the low flow rate in gallons per minute or cubic feet per second on the left-hand scale. Remember, if some water must be left in the stream, the power potential will. be reduced. Next, ~locate the total available head on the right-hand scale. Connect these points with a straight line. On the middle scale, read the kilowatt potential (capacity) at the point where the straight line crosses. This is the approximate number of kilowatts the stream will produce. Energy can be thought of as a running total of power in kilowatts (1000 Watts) over time in hours, as expressed in kilowatt-hours (kWh). For example, a hydroelectric system generating at a lOkW power output for one hour will produce 10 kWh of electrical energy. Energy production is very sen- sitive to the maximum flow that the turbine and pipe can accoiTIIlOdate and to the variable volume of available water. If these volumes can be estimated for different times of the year, energy (E) can be calculated as: ·~ E = p X t where P = power in kW t = time intervals in hours In part, the sizing of a stand-alone hydroplant depends upon the demand for electricity. In actual practice a typical house may have a peak demand of about SkW. This means that at some time during a typical month there will be a period during which the household will be consuming power at a rate of 5 kW. A large group of houses together would have an average peak demand of about 2.5 kW per home, and an average demand of 1.4 kW. The average peak demand per house is reduced for the group, because not .all appliances are in use at the same time, and the more houses, the more the peak is spread out. This would indicate that a stand-alone 100-kW plant could actually supply the·energy needs of 35 to 40 homes, assuming that the annual production is 50% of the. theoretical maximum from the 100 kW plant. If a 100-kW hydropower plant is used in place of diesel power units, the plant would displace diesel fuel at the rate of 10 gallons per hour, or about 88,000 gallons per year. In the case of Ship Creek in south coastal Alaska, the creek has a drainage area of 90 square miles and has been gaged for 39 years. The ~verage annual flow is 163 cfs. Now suppose some idea of minimum flow were needed on a stream with 30 square miles of drainage area which had basin characteristics similar to Ship Creek. As an approximation, the annual flow of the stream in proportion to the drainage a rea is: 163 cfs x (30 + 90) = 54 cfs average annual daily flow. The yearly flow for the stream would be 54 cfs X 365 days = 19,700 cfs-days. The chart for a low elevation mountain stream in South- central Alaska shows that the minimum percentage of annual flow occurs in February and is about 2.3% of the annual flow. Calculating the low flow for the stream in question results in: .023 x 19,700 cfs-days = 453 cfs-days. February has 28 days, so dividing 453 by 28 provides cfs/day: 453 cfs-days/28 days = 16 cfs minimum flow. An approximate power generation capability can be determined from this minimum value. For example, for 30 foot of head and a typical turbine generation output of about 6 KW/cfs/100' of head, the output would be: 30 feet/100 feet X 6 KW/cfs X 16 cfs = 29 KW. If a hydro system will produce electricity for a house- hold, it will often be a DC-to-AC conversion system, requir- ing only minimum flows. If, however, a considerably larger system is envisioned, a direct AC system design would be chosen. In this case load projections will have to be calculated, particularly with respect to what can be done with the energy at the time of year it is available. This will require some information regarding maximum and mean stream flows as well as minimum. If the system requires, a dam, it will be vital to know maximum stream flows in order to size spillways adequately to bypass excess water and prevent damaging the installation. OTHER METHODS OF MEASUREMENT: • Container Filler Time For small mountain streams or springs, temporarily dam up the water and divert the entire flow into a container of known size. Carefully time the number of seconds it takes to fill this container. For example, if the filling times for a 55 gallon drum, placed under a culvert, averaged 20 seconds, the flow rate would be: 55 gal/20sec = 2.75ga1/sec x 60sec/min = 165gpm = .37cfs • Float Method Flow can also be estimated using a watch, tape measure, weighted float, and calibrated stick such as a yardstick for shallow streams. A float can be made using either a piece of wood weighted at one end with some heavy material -such as nails or metal scraps -or a plastic container partially filled with water. The float is partially submerged to ob- tain a better estimate of the average stream velodty, but should not touch the bottom of the stream. Begin by finding a stretch of stream as straight and as uniform in width and depth as possible. Pick a typical section and measure the stream width (W) with the tape measure. Use the calibrated stick vertically to measure the depth at 6-inch intervals across the stream. Nine depth measurements, including two zero measurements at the stream banks, are shown in Illustration 10. Average these depths to estimate the average stream depth (D). Multiply the average depth by the stream width to estimate the stream area (A). w . ; ...... •. .•:. ": ·4 • ., • ~ • ~ . ~.::· .. ·: 7..,.:.·:.=: ..... ··:: ..... .. · .... '. Averaga d-th: Stream araa: c .. 0 + o, + 02 + 03 + 04 .. os + 06 + 07 + 0 A= DxW ' I. 10 The stream velocity can be determined by choosing a straight stretch of water at least 30 feet long with sides approximately parallel and the bed unobstructed by rocks, branches or other obstacles. Mark off two points approx- imately 20 feet apart along the stream. On a windless day, place a float upstream on the first marker, in midstream. Carefully time the float's travel between markers. Repeat several times at different distances across the stream's width. Use the average time and the measured distance to calculate the average velocity. Flow can be calculated from the equation: Q = A X v X c. where Q = water flow rate, A = stream area, V = average stream velocity, C = correction factor. The flow equation includes a correction factor to account for streambed conditions. Use C = 0.8 for a smooth streambed; or C = 0.7 for intennediate conditions; C = 0.6 for a rough or rocky streambed. Flow is calculated in cubic feet per second (cfs), based on area in square feet and velocity in feet per second. For other units of measure, see the conversion table at the end of this booklet. Flow measurements must be made several times over a year to detennine flow variability. For rough estimates, several measurements using the float method would do. Remember that both the stream area and velocity change with flow rate, so that depth, width, and velocity must be measured each time. A more complex and accurate measurement technique is achieved by building a weir across the stream . . '. ·._; · .. · .. 9: .. :· .:-->~-/ .. :-~ -:--::·-.:~-~: .. :_·-~-: : ~ ::<<< ·:· ~ ~ < -·:-.. Flow _ 1st Float __. • 3rd r:t_oat ~ .... -2_nd _FI_Oa t _.. -_-._ -,, --·L:-~n~ih-.t~;--~-~ming~-·L -_: ~>· :·:~ ~ Average time: T : T1 + Tz + TJ 3 Stream velocity: L v =-r Stream flow: Q a AxVxC Float metllod of meaiiW"Ing average atream velocity. I 1 1 • Weir Method A weir, as used in flow measurement, is a temporary dam built across the stream perpendicular to the flow. A rectan- gular notch or spillway of predetermined proportions is 1 oca ted in the center section. The notch has to be 1 a rge enough to take the maximum flow of the stream during the period of measurement, so make some rough estimate of the stream flow prior to building the weir. The notcn width (W) should beat least three times its height (H), and the lower edge should be perfectly level. The lower edge and the vertical sides of the notch should be beveled with the sharp edge upstream. The whole structure can be best built out of timber with all edges and bottom sealed with clay. earth and sandbags to prevent any leakage. A typical weir is shown in Illustration 12. In order to measure the flow of water over the weir, set up a simple depth gage. This is done by driving a post in the stream bed at least 5 feet upstream from the weir, until a pre-set mark in the post is precisely level with the bottom edge of the spillway. The depth of water above the pre-set mark will indicate the flow rate of water over the weir. You will need to refer to a nwefr Table" in order to determine this flow rate. (See Table 11) Weir and Depth Gage I. 12 Table 11 WEIR TABLE Inches 0 1/8 1/4 3/8 1/2 5/8 3/4 7/8 0 0 0.003 0.008 0.0015 0.0024 0.0033 0.0044 0.0055 1 O.OC67 0.0080 0.0094 0.0108 0.0123 0.0139 0.0155 0.0172 2 0.0190 0.0208 0.0226 0.0245 0.0265 0.0285 0.0306 0.0327 3 0.0348 0.0370 0.0393 0.0415 0.0439 0.0462 0.0487 0.0511 4 0.0536 0.0561 0.0587 0.0613 0.0640 0.0666 0.0694 0.0721 5 0.0749 0.0777 0.0806 0.0835 0.0864 0.0894 0.0924 0.0954 6 0.0985 0.1016 0.1047 0.1078 0.1110 0.1142 0. !'175 0.1208 7 0.1241 0.1274 0.1308 0.1342 0.1376 0.1411 0.1446 0.1481 8 0.1516 0.1552 0.1588 0.1624 0.1660 0.1697 0.1734 0.1771 9 0.1809 0.1847 0.1885 0.1923 0.1962 0.2001 0.2040 0.2079 10 0.2119 0.2159 0.2199 0.2239 0.2280 0.2320 0.2361 0.2403 11 0.2444 0.2486 0.2528 0.2570 0.2613 0.2656 0.2699 0.2742 12 0.2785 0.2829 0.2873 0.2917 0.2961 0.3006 0.3050 0.3095 13 0.3140 0.3186 0.3231 0.3277 0.3323 0.3370 0.3416 0.3463 14 0.3510 0.3557 0.3604 0.3652 0.3699 0.3747 0.3795 0.3844 15 0.3892 0.3941 0.3990 0.4039 0.4089 0.4138 0.4188 0.4238 16 0.4288 0.4338 0.4389 0.4440 0.4491 0.4547 0.4593 0.4645 17 0.4696 0.4748 0.4800 0.4852 0.4905 0.4958 0.5010 0.5063 18 0.5117 0.5170 0.5224 0.5277 0.5331 0.5385 0.5440 0.5494 19 0.5549 0.5604 0.5659 0.5714 0.5769 0.5825 0.5881 0.5937 20 0.5993 0.6049 0.6105 0.6162 0.6219 0.6276 0.6333 0.6390 21 0.6448 0.6505 0.6563 0.6621 0.6679 0.6738 0.6796 0.6855 22 0.6914 0.6973 0.7032 0.7091 0. 7151 0.7210 0.7270 0.7330 23 0.7390 0.7451 0. 7511 0.7572 0.7633 0.7694 0.7755 0.7816 24 0.7878 0. 7939 0.8001 0.8063 0.8125 0.8187 0.8250 0.8312 25 0.8375 0.8438 0.8501 0.8564 0.8628 0.8691 0.8755 0.8819 26 0.8882 0.8947 0.9011 0.9075 0.9140 0.9205 0.9270 0.9335 27 0.9400 0.9465 0.9531 0.9596 0.9662 0.9728 0.9792 0.9860 28 0.9927 0.9993 1.006 1.013 1.019 1.026 1.033 1.040 29 1.046 1.053 1.060 1.067 1.074 1.080 1.087 1.094 30 1.101 1.108 1.115 1.122 1.129 1.136 1.152 1.149 31 1.156 1.163 1.170 1.178 1.184 1.192 1.199 1.206 32 1.213 1.220 1.227 1.234 1.241 1.248 1.256 1.263 33 1.270 1.227 1.285 1.292 1.299 1.306 1.314 1.321 34 1.328 1.336 1.343 1.356 1.358 1.365 1.372 1.378 35 1.387 1.395 1.402 1.410 1.417 1.425 1.432 1.440 Flow per Inch of Weir Width (cfs) To use the table, determine the depth of water in inches above the post notch. The table lists flow for each inch of weir width. To establish total flow, multiply the volume flow rate by width, in inches, of the weir notch. This will give the stream flow rate in cubic feet per second. While the weir is in place, readings can be taken at convenient intervals. If the weir will be in place for any extended period of time, it is important to frequently check the watertightness of the sides and bottom. Note: Weir construction shouLd onty be undertaken with appropriate permits. Contact Division of Land and Water Management (DNRJ and other agencies referenced in Sec- tion III. HEAD LOSSES The greater the vertical distance water falls the more potentially useful power is available from it. For high head systems~ detailed topographica 1 maps of the area may give some indication of the vertical height difference between proposed intake and tailwater levels. The degree of accuracy attainable from map readings is limited, so this technique should only be used for very preliminary estima- tions. More comprehensive methods of head measurement are necessary for both the independent developer and those who wish to interconnect to an existing electrical grid. In the former case. when miniiiUII flow values are known and power needs have been calculated, a design head can be computed to determine an approximate intake location. The basic hydro power equation given earlier solves for kW capacity: p _ Q X H X e -11.8 where P = design capacity in kW Q = flow in cfs H = head in feet e = system efficiency 11.8 = conversion factor for water density Rewriting the equation to solve for H produces the follow- ing: H = 11.8 X P Q x e Theoretically, provided topography and other factors were feasible, the design head could then be located for further conceptual examination. Where head is subject to variation to satisfy design requirements, more precise methods of measeurements are available. Several of these are given below. METHODS FOR MEASURING HEAD •Estimating Head Through Water Pressure Head and water pressure are directly proportional: 1 foot o.f ~.ead = ,.433 lbs per square inch {psi) Using this relationship, head can be measured in relatively short river increments using a static pressure gage and hose. A gage with 0.1 psi accuracy and hose of less than 20 feet are required. Starting at the tailrace location of the turbine or other power unit, the hose is submerged so water flows freely through it. The upper end of the hose ought to have an elbow joint attached to direct the opening to goo from the upstream direction in order to compensate for effects from water velocity. The lower end then has the pressure gage attached for a measurement. Noting the location of the upper end of the hose, successive measurements and readings are taken until the intake location is reached. The sum of all the readings divided by .433 equals pool-to·pool head in feet. p + p 2 + p n h =--""rlrl--...;. .433 where h = head in feet P = individual measurements n = number of measurements .433 = pressure per foot of head • Photographic Surveying For those who are acquainted with photographic surveying techniques, this method of head measurement can give fairly accurate results. Pictures taken in the field can be developed and the elevations scaled on the photo- graphs. But caution --this is not a method for amateurs. Photographic surveying requires some skill and training. • Altimeter Measurements Pocket altimeters can give preliminary estimations of the elevation difference between intake and tailwater lo- cations on proposed high head systems. The accuracy of these measurements is not suitable for any serious calcula- tions. Larger portable altimeters tend to be very expensive, but enable elevation measurements to an accuracy of a couple of feet. These instruments are suitable for engineering calculations and can be rented from retail outlets for surveyor's equipment. • Surveying A surveyor can be hired to determine the head. The surveyor will calculate the vertical distance between water source, or proposed intake location, and the proposed location of the power plant. Because this approach may be expensive, reasonable assurance of carrying through with the project is recommended. If the head is less than 25 feet, very precise measurements are required and a surveyor is advisable. If you know how to use standard surveying equipment (transit or a surveyor's level and leveling rod), borrow or rent the equipment and get a friend or two to help you make the necessary measurements. eLevel & Tape Measure Another do-it-yourself technique involves a carpenter's level, some sort of table to raise the level a few feet off the ground, and a tape measure. The assistance of a second person may also be required. The ''plane table and aledaide" method is described below and shown in the following illustration: 1. Set the level on the stand; make sure the level is horizontal (level) and that its upper edge is either at the same elevation as the water source, or a known vertical distance above the water surface (height of the stand plus width of level). 2. Sight along the upper edge of the level to a spot on a nearby object (tree, rock, building) that is further downhill and which can be reached for mea- suring. Level & Tape Method START AT PLACE WHERE WATER I INTAKE WOULD OCCUR ~ MEASURING STICK HELD STRAIGHT UP BY 2ND PERSON Al H=HEIGHT OF LEVEL FROM SURFACE OF WATER RECORD HEIGHTS ABl FEET AB2 FEET AB3 FEET qc. FEET -TOTAL DROP ---IN ELEVATION - SUBTRACT HEIGHT OF LEVEL ABOVE WATER AT 1ST -H MEASUREMENT ---TOTAL ELEVATION DROP OR "HEAD" I. 13 STOP MEASURING AT PLACE WHERE POWER FACILITY WOULD GO 3. Note this precise spot on the object and mark it (point A in the diagram). 4. Move the level and stand down the slope and set it up again so that this time the upper edge of the level is at some point B, below point A on the first object, as shown in the drawing. Mark this point B and measure and record the vertical distance A to B. Now sight along the upper edge of the level in the opposite direction to another object that is further downhill. - 5. Repeat this procedure until the elevation of the proposed power plant site is reached. 6. If more than one set up was required, add all the vertical distances A·B. If the first set up was above the water surface, subtract the vertical distance between the water surface and the upper edge of the level from the sum of the vertical distances. You now have the total head. • You do not need to be concerned with horizon- tal distances for head determination. • Every time you re-set the level, its upper edge should be at precisely the same level as Point B (sight back to check). • You need not travel in a straight line. HEAD & SYSTEM LOSSES • Penstock Effects Once total or gross head has been determined, various losses must be considered before further theoretical power calculations can be made. The net head is required for these calculations • .. ,-G-ro_s_s_H-ea-d---lo_s_s_e_s_=_N_e_t-He_a_d_, Losses occur through friction and are greater as flow velocity increases or pipe diameter decreases. Variation in slope, intake and valve constrictions, and the turbine itself may all contribute to some inherent head loss, but the most severe area of concern is related to the pipe or FLOW OF WATER IN PIPES HAZEN WILLIAMS NOMOGRAPHIC CHART 10 200 100,000 9 8 7 e 100 5 4 3 10.000 Cl) w z 0 0 z z > 0 500 0 .... I 0 w 1-(I) 0 3 18 a: ... 0 w w z Q. 200 > 0 1&1 I 0 .... .... w :) > LL. w z 0 LL. 100j a: 12 0 1&1 -a: .... • w w :) Q. ::1 0 50 < 10 I «t Q z w 0 I c:l ... 0 ~ .05 ... 20 < 8 z c:l 0 cd !2 Q 10 ::$ I .02 I a a e 5 5 2 4 1 ....: u. 0 0 .3 1-0 z -w a: .4 ii: w LL. a. .5 w ; r·· 1-w .6 w .7 u. .8 0 .9 2 100 < 1 w a: w z LL. z ::::; u. 1-0 0 0 en :> en 2 0: 0 ~ 3 4 5 e 7 8 9 10 20 A Nomograph to Determine Losses Due to Friction in PVC Pipe ********** In summary, the steps to follow to determine the hydro potential of a site are: 1. Measure the water flow rate using one of the following: 2. 3. 4. s. -available or extrapolated data, -timed container filling method, -float method, -weir method. Determine the usable flow, with attention to minimum flow and possible development of a flow duration curve. Measure the total or gross head, -pressure method, -surveyor•s equipment, -carpenter•s level and stand. Determine the net head by subtracting friction and other losses from the gross head. Calculate the theoretical power available using 6. Calculate the useful power available by multi- plying theoretical power by the efficiency of each piece of machinery linked into the system between and including the water wheel or turbine and the unit giving out the useful power. Embankment dam -Wikipedia, the free encyclopedia Embankment dam F... Wikipedia, the free encyclopedia An embankment dam is a massive artificial water barrier. It is typically created by the emplacement and compaction of a complex semi-plastic mound of various compositions of soil, sand, clay and/or rock. It has a semi-permanent waterproof natural covering for its surface, and a dense, waterproof core. This makes such a dam impervious to surface or seepage erosion . l 11 The force of the impoundment creates a downward thrust upon the mass of the dam, greatly increasing the weight of the dam on its foundation. This added force effectively seals and makes waterproof the underlying foundation of the dam , at the interface between the dam and its stream bed.l21 Such a ·dam is composed of fragmented independent material particles. The friction and interaction of particles binds the particles together into a stable .mass rather than the ~se of a cemer ting substance.l31 !Contents ! I l l • 1 Types ~ 1 • 2 Safety I • 3 See also I 4 Notes 1 5 External links '-·--------· Types Embankment dams come in two types: the earth-filled dam (also called an earthen dam or terrain dam) made of compacted earth, and the rock-filled dam. A cross-section of an embankment dam shows a shape like a bank, or hill. Most have a central section or core composed of an impermeable material to stop water from seeping through the dam. The core can be of clay, concrete or asphalt concrete. This dam type is a good choice for sites with wide valleys . Since they exert little pressure on their foundations , they can be built on hard rock or softer soils . For a rockfill dam , rockfill is blasted using explosives to break the rock. Additionally. the rock pieces may need to be crushed into smaller chunks to get the right range of size for use in an embankment dam . l41 !~ety Page 1 of 3 San Luis Dam - Embankment dam Tarbela Dam, the world's largest embankment dam Pothundi Dam, India file://G:\Em bankment%20dam %20 .. %20Wikipedia, %20the%20free%20encyclopedia. htm 1 0/7/2008 '::.mOarJKIIIt:l ll Udlll -VVIr-!!Jt:Uia, lilt: II vv vllvJ'-'IVtJY''-'10 The building of a dam and the filling of the reservoir behind it places a new weight on the floor and sides of a valley. The stress of the water increases linearly with its depth. Water also pushes against tt-~ ·~pstream face of the dam, a nonrigid structure that under stress behaves semiplastically, and c... Jes greater need for adjustment (flexibility) near the base of the dam than at shallower water levels. Thus the stress level of the dam must be calculated in advance of building to ensure that its break level threshold is not exceeded. [S] Overtopping or overflow of an embankment dam outside of its spillways will cause disastrous flooding through the eventual failure of the dam. In the failure process the sustained hydraulic force and pressure caused by an overtopping surface runoff; immediately erodes the dam's material structure as it flows over the top of the dam. Even a small sustained overtopping surface flow can remove thousands of tons of overburden soil from the mass of the dam within hours. The removal of this mass unbalances the forces that stabilize the dam against its impoundment. The mass of water still impounded behind the dam presses against the lighter mass of the embankment, (made lighter by surface erosion). As the mass of the dam gets lighter, the impoundment begins to move the whole structure. The embankment, having almost no elastic strength, begins to break into separate pieces, naturally allowing the impounded water to flow between them eroding and removing more material as it goes. In the final stages of failure the remaining pieces of the embankment offer almost no resistance to the flow of the water; as they continue to fracture into smaller and smaller sections of earth and/or rock. The overtopped earth embankment dam literally disolves into a thick mud soup of earth, rocks and water. Therefore safety requirements for the spillway are high, requiring the spillway to be capable of containing a maximum flood stage. Specifying a spillway able to contain a five hundred year flood is c mon.r6l See also • Dam • Arch-gravity dam Notes 1. ""Dam Basics (http://www.pbs.org/wgbh/buildingbig/dam/basics.html#emb)". PBS. Retrieved on 2007..02-03. 2. " "Embankment dam: forces (http://www.pbs.org/wgbh/buildingbig/dam/emb forces.html)". PBS. Retrieved on 2007-02-03. - 3. ""Introduction to rock filled dams (http://www.dur.ac.ukl-des0www4/cal/dams/emba/embaf17.htm)". Retrieved on 2007-02-05. 4. ""About Dams (http://www.britishdams.org/about_dams/embankment.htm)". Retrieved on 2007-02-03. 5. " "Pressures Associated with Dams and Reservoirs (http://www.dur.ac.ukl-des0www4/cal/dams/foun/founf5.htm)". Retrieved on 2007..02-05. 6. ""Dams-Appurtenant Features (http://www.dur.ac.ukl-des0www4/cal/dams/intr/intrf4.htm)". Retrieved on 2007..02-05. l Jernal links fi le://G:\Em bankment%20dam %20-%20Wikipedia, %20the%20free%20encycloped ia. htm 10/7/2008 Away from the dam itself, the powerhouse, instrument buildings, and even homes for resident operators of the dam are also finished. Initial tests of all the facilities of the dam are performed. 6. The final details of constructions are wrapped up as the dam is put into service. The beginning of the dam's working life was also carefully scheduled as a design item, so that water is available in the reservoir as soon as the supply system is ready to pump and pipe it downstream, for example. ,A program of operations, routine maintenance, rehabilitation, safety checks, instrument monitoring, and detailed observation will continue and is mandated by law as long as the dam exists. Quality Control There is no dam construction without intensive quality control. The process of building alone involves heavy equipment and dangerous conditions for construction workers as well as the public. The population living downstream of the dam has to be protected over the structure itself; the professionals who design and construct these projects are absolutely committed to safety, and they are monitored by local, state, and federal agencies like Divisions of Dam Safety, the U.S. Corps of Engineers, and the Department of Reclamation. Byproducts/Waste There are no byproducts in dam design or construction although a number of other associated or support facilities may be needed to make the project work. Waste is also minimal because materials are too expensive for waste to be allowed. Also, locations are often remote, and the process of hauling waste away from the site and disposing it is prohibitive. Soil and rock that may be excavated from the foundation area, down-stream sites, the abutments, or portions of the reservoir are usually used elsewhere on the project site. Quantities of materials cut away or placed as fill are carefully calculated to balance. The Future The future of concrete dams is the subject of much debate. Each year, over 100,000 lives are lost in floods, and flood control i~ a major reason for building dams, as well as protecting estuaries against flooding tides and improving navigation. Lives are also benefited by dams because they provide water supplies for irr~gating fields and for drinking water, and hydroelectric power is a non-polluting source of electricity. Reservoirs are also enjoyed for recreation, tourism, and fisheries. However, dams are also damaging to the environment. They can change ecosystems, drown forests and wildlife (including endangered species), change water quality and sedimentation patterns, cause loss of agricultural lands and fertile soil, regulate river flows, spread disease (by creating large reservoirs that are home to disease-bearing insects), and perhaps even affect climate. There are also adverse social effects because human populations are displaced and not satisfactorily resettled. For years before the start of construction in 1994 of the Three Gorges Dam in China, environmentalists the world over organized protests to try to stop this huge project. They have not succeeded, but controversy over this project is representative of the arguments all proposed dams will face in the future. The balance between meeting human needs for water, power, and flood control and protecting the environment from human eradication or encroachment must be carefully weighed. Where to Learn More Books Bureau of Reclamation, U.S. Department of the Interior. Design of Sam II Dams. Washington, DC: U.S. Government Printing Office, 1977. Jansen, Robert B. Dams and Public Safety. Washington, DC: U.S. Dept. of the Interior, Water and Power Resources Service, 1980. Krynine, Dimitri P. and William L Judd. Principles of Engineering Geology and Geotechnics. New York: McGraw-Hill Book Co., Inc., 1957. Smith, Norman. A History of Dams. Secaucus, New Jersey: The Citadel Press, 1972. Periodicals Bequette, France. "Large Dams." UNESCO Courier (March 1997): 44. Cotrim, John, et al. "ltaipu: South America's Power Play. 11 Civil Engineering (December 1984): 40. Filion, Mike. "Taming the Yangtze: lauded and lambasted, China's Three Gorges Dam may be the biggest civil-engineering project ever." Popular Mechanics (July 1996): 52. Mor~es, Julival de, et al. "ltaipu: Part 1." [ltaipu Hydroelectric Project, Brazrl/Panama] Construction News Magazine (March 1982): 18. Moraes, Julival de, et al. "ltaipu: Part 2." Construction News Magazine (April 1982): 22. Concrete Dam How Products Are Made Concrete Dam Background Index of research topics I Index of publicatior Print Concrete dams are built in four basic shapes. The concrete gravity dam has weight as its strength. A cross section of this dam looks like a triangle, and the wide base is about three-fourths of the height of the dam. Water in the reservoir upstream of the dam pushes horizontally against the dam, and the weight of the gravity dam pushes downward to counteract the water pressure. The concrete buttress dam also uses its weight to resist the water force. However, it is narrower and has buttresses at the base or toe of the dam on the downstream side. These buttresses may be narrow walls extending out from the face of the dam, much like the "flying buttresses" supporting cathedral walls or a single buttress rather like a short dam may be built along the width of the toe of the dam. The arch dam is one of the most elegant of civil engineering structures. In cross section, the dam is narrow in width, but, when viewed from above, it is curved so the arch faces the water and the bowl of the curve looks downstream. This design uses the properties of concrete as its strength. Concrete is not strong in tension (when it is pulled or stretched), but it is very strong in compression (when it is pushed or weighed down). The arch dam uses the weight of the water behind it to push against the concrete and close any joints; the force of the water is part of the design of the dam. The arch-gravity dam is a combination of the arch type and gravity type, as the name suggests; it is a wider arch shape. Multiple-arch dams combine the technology of arch and buttress designs with a number of single arches supported by buttresses. Concrete dams are used more often than fill dams to produce hydroelectric power because gates (also called sluices) or other kinds of outlet structures. can be built into the concrete to allow for water to be released from the reservoir in a controlled manner. When water for power, drinking water, or irrigation is needed downstream, the gates can be opened to release the amount needed over a specified time. Water can be kept flowing in the river downstream so fish and other wildlife can survive. Both concrete and fill dams are required to have emergency spillways so that flood waters can be safely released downstream before the water flows over the top or crest of the dam and potentially erodes it. Spillways channel the water downstream and well below the base or toe of the dam so the dam and its foundation are not eroded. Most dams built in the twentieth century and those being designed today have several purposes. Over 40,000 dams higher than 45ft {15m) and classified as large dams exist, and more than half of these have been built since 1960. Of these dams, 16% of them are in the United States and 52% are in China; 83% are fill dams used primarily for water storage, and the remaining 17% are concrete or masonry dams with multiple purposes. Dams that generate hydroelectric power produce 20% of the electricity in the world. History Fill dams may be a far older construction technique than concrete or masonry dams, but the oldest surviving dam is Sadd el Kafara about 20 mi {32 km) south of Cairo, Egypt. This dam is actually a composite consisting of two masonry walls with the space between filled with gravel; it was built between 2,950 and 2,750 b.c. The ancient Romans developed superior techniques for building with masonry, but, curiously, they did not often use their masonry skills in dam construction. An exception was the Proserpina Dam in Merida, Spain, that is still standing today. Developments by the Romans were not overlooked by others. In about 550a.d., the Byzantines on the eastern fringes of the Roman Empire used the shape of the Roman masonry arch to build what history believes was the world's first arch- gravity dam. Dam building came to America with the conquistadors. In Mexico, they saw dry land in need of irrigation and imitated the dams built by the Romans, Muslims, and Spanish Christians in their homeland; the Catholic Church financed construction, and many of the missionaries were skilled engineers. Dam building was rare in Europe until the Industrial Revolution. The northern climates produced more rainfall, so water power was naturally occurring and water supply was plentiful. In the eighteenth century, however, the rise of industry necessitated constant, reliable supplies of water power delivered at greater force, so masonry and concrete dam construction became popular in Europe. The Industrial Revolution also powered developments in science and engineering, and the civil engineering specialty, which includes designing and building structures to better the quality of life, came into existence in the 1850s. Early civil engineers began to study Sir Isaac Newton's physics and other scientific theories and apply them to practical structures including dams. On September 30, 1911, the town of Austin (population 3,200) in the mountainous country of north central Pennsylvania was ravaged by a torrent of water roaring through the valley, channeled by its narrowness and rugged walls. The force ripped gas mains from beneath the streets; and as soon as the wall of water passed, an errant flame lit the gas and the fire jumped from gas pipe to gas pipe and house to building throughout the standing remains of the 30-year-old town of Austin. Initial reports claimed that 1,000 people had perished, although later information placed the death toll at between 50 and 149. The source of this grief was also the source of livelihood for Austin. The Bayless Pulp and Paper Mill owned the concrete dam, which it had constructed in 1909 to provide a water storage reservoir for its water-intensive pulp-and papermaking business. There had been a precursor to this disaster in January 1910 when, following intense winter rain and snowmelt, cracks had been observed in the dam. The cracks were repaired, but they were not recognized as indications of problems related to the foundation, design, and construction of the structure. The dam was still under construction as the winter of 1909-10 approached. Temperatures were below freezing when some of the concrete was placed, and the final stages of construction were finished hurriedly. The dam was completed on about December 1, 1909, and a crack running from the crest of the dam vertically to the ground was visible when construction was finished. By the end of the month, a second crack had appeared. Both cracks seemed to have resulted from contraction of the concrete. On January 17, 1910, a warm spell brought heavy rains and caused rapid snowmelt, and four days later, flood water was pouring over the spillway. All technical aspects of Austin Dam were poor. The construction failures were obvious and included use of weak, oversized aggregate placed in improperly cured concrete in freezing weather. When the January 1910 failure occurred, it showed that the dam structure and the founding bedrock had failed. The owner/operator's disregard of the engineer's recommend-ed repairs was the fatal seal. Raw materials The key raw materials for concrete dams are concrete itself and steel reinforcement. number of other materials and components made by specialty contractors may be used in dam building and include steel gates and tunnel liners, rubber waterstops, plastic joint-filling compounds to prohibit the movement of water, electrical controls and wiring, siphons, valves, power generators, a wide assortment of instruments, and even Teflon sheeting to line water outlet structures to prevent turbulence and cavitation (damage due to swirling water). Concrete itself is made of cement, water, and materials collectively called aggregate that consist of sand or gravel. Cement has unique properties that must be considered in selecting the cement, designing the dam, and timing construction. Mixing of cement and water causes a chemical reaction that makes concrete hard but that also releases heat This causes a distinct rise in the temperature inside a mass of concrete, and, when the concrete begins to cool, it shrinks and cracks, potentially causing leaks. To limit these effects, concrete can be placed when the air temperature is low, low-heat cement can be used, and water can be circulated through pipes in the concrete. Furthermore, the concrete has to be placed in shallow lifts (i.e., only a few feet or meters are added at a time) and in narrow blocks; then it has to be allowed to cure over a specified minimum time so the heat dissipates. Depending on the design of the dam, engineers will choose the concrete mix (including the cement and type of aggregate) very carefully; a thin arch dam is designed with a different concrete mix than a massive gravity dam. Design Design of a concrete dam depends on the purpose of the dam and the configuration of the site where it will be built. Dams are of two general types. Overflow dams block flow in a stream and harness the water for generating power or to improve navigation and provide irrigation water. The components of an overflow dam are designed so the water can be released and the level of the water in the reservoir regulated by a series of sluice gates, spillways, or outlet tunnels. Non-overflow dams store water for drinking water supply, irrigation, or power; they also have a spillway, but its use is restricted for emergencies to lower the water level quickly during floods. Methods for releasing the stored water are much more limited than in overflow dams, and the dam itself may not contain any outlet structures. Instead, water may be pumped out for irrigation, for example, from part of the reservoir. Some sites are best suited to particular types of dams. An arch dam is most appropriate for construction in a high, narrow gorge where the arch of the structural shape provides strength. But an arch can also be built across a wider canyon where other effects like friction on the base of the dam add strength and resistance to movement. Similarly, a gravity dam is the typical choice for a shallow, wide canyon, but if it is built with some curvature, arching action will also strengthen a gravity dam in a narrower and higher gorge. Where the riverbed is exceptionally wide, the dam may be designed to have several spans, each with different engineering properties depending on the variation of foundation materials. The separate spans are usually supported on the downstream (air) side by buttresses or the extended curves of multiple arches. Sometimes, the spans of multiple span dams are constructed of concrete slabs or steel plates supported on piers. Like fill dams, concrete dams go through extensive rounds of preliminary design and feasibility studies to choose and explore the site, to evaluate the quantity of water retained and ·its value (as a power source or source of supply) versus the cost of the project over the anticipated years of operation, to consider a wide range of other effects such as changes to the environment, and to choose a dam of the optimal size and configuration. Hundreds of factors enter into these studies, and the process is usually iterative. A design is chosen and tested against all these factors until it fails to satisfy one or more factors, and the next variation in design is chosen and studied until it fails-or passes. The design process for a concrete dam typically involves professionals from a more extensive range of disciplines than design of a fill dam. The technical professionals who contribute their expertise to design of a concrete dam may include geologists, seismologists, environmental scientists, geotechnical (soil) engineers, civil engineers, structural engineers, computer analysts (specialists in software applications that examine the dam's strength and safety), hydrologists and hydraulic engineers, mechanical engineers, and electrical engineers if the dam is to be used for power generation. Still more specialists may study aspects like corrosion of concrete and steel structures. The teamwork required for dam design and construction is critical not only because of the enormous costs of these projects but because the safety of persons and property downstream demands perfection. The Construction Process 1. Before construction can begin on any dam, the water in the streambed must be diverted or stopped from flowing through the site. As in the case of fill dams, a coffer-dam (a temporary structure to impound the water)must be built or the water must be diverted into another channel or area down-stream from the dam site. For large projects, this construction may be done several seasons before building of the dam begins. The flow of water is closed off at the very last moment. 2. The foundation area for any concrete dam must be immaculate before the first concrete for the dam is placed. As for fill dams, this is a detailed process of excavating, cleaning, and repairing the rock throughout the foundation "footprint" and on both abutments (the sides of the canyon that form the ends of the dam). Sites immediately downstream of the dam for any powerplant, stilling basin, or other structure must also be prepared. At some sites, extensive work may be required. If the rock in the foundation or abutments is prone to fracturing because of the load imposed by the dam and its reservoir, earthquake activity, or the properties of the rock, it may be necessary to install extensive systems of rock bolts or anchor bolts that are grouted into the rock through potential fracture zones. On the abutments above the dam, systems of rock bolts and netting may be required to keep large rock fragments from falling onto the dam. Instruments to monitor groundwater levels, joiQt movement, potential seepage, slope movements, and seismic activity are installed beginning during the early stages of foundation preparation through completion of the dam. A cutoff wall may be excavated deep into rock or holes may be drilled in the foundation for the installation of reinforcing steel, called rebars, that extend up into the dam and will be tied to the steel inside the first lifts of the dam. The idea is to build a reservoir that, like a bowl, is equally sound around its perimeter. The water is deepest and heaviest at the dam (when the reservoir is near capacity) so the dam and its foundation cannot be a weak point in that perimeter. 3. Forms made of wood or steel are constructed along the edges of each section of the dam. Rebar is placed inside the forms and tied to any adjacent rebar that was previously installed. The concrete is then poured or pumped in. The height of each lift of concrete is typically only 5-10ft (1.5-3 m) and the length and width of each dam section to be poured as a unit is only about 50ft ( 15 m). Construction continues in this way as the dam is raised section by section and lift by lift. Some major dams are built in sections called blocks with keys or inter-locks that link adjacent blocks as well as structural steel connections. The process is much like constructing a building except that the dam has far less internal space; surprisingly, however, major concrete dams have observation galleries at various levels so the condition of the inside of the dam can be observed for seepage and movement. Inlet and outlet tunnels or other structures also pass through concrete dams, making them very different from fill dams that have as few structures penetrating the mass of the dam as possible. 4. As soon as a significant portion of the dam is built, the process of filling the reservoir may begin. This is done in a highly controlled manner to evaluate the stresses on the dam and observe its early performance. A temporary emergency spillway is constructed if dam building takes more than one construction season; lengthy construction is usually done in phases called stages, but each stage is fully complete in itself and is an operational dam. The upstream cofferdam may be left in place as a temporary precaution, but it is not usually designed to hold more than minimal stream flows and rainfall and will be dismantled as soon as practical. Depending on design, some dams are not filled until construction is essentially complete. 5. The other structures that make the dam operational are added as soon as the elevation of the their location is reached as the dam rises. The final components are erosion protection on the upstream (water) side of the dam (and sometimes downstream at the bases of outlet structures}, instruments along the crest (top) of the dam, and roads, side-walks, streetlights, and retaining walls. A major dam like Hoover Dam has a full-. fledged roadway along its crest; small dams will have maintenance roads that allow single-file access of vehicles only. Penstock From Wikipedia, the free encyclopedia SJ Penstocks at the Ohakud Dam, New Zealand. 6=1 Penstock cross-section. A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydraulic turbines and sewerage systems . It is a term that has been inherited from the technology of wooden watermills. Contents • 1 In hydro-elec~ric systems and dams • 2 In watermills • 3 Similar structpres • 4 External links [edit] In hydro-electric systems and dams Penstocks for l1yilloelectric installations are normally equipped with a gate system and a surge..talli;. Flow is regulated by turbine operation and is nil when turbines are not in service. Maintenance requirements may include hot water wash, manual cleaning, antifoulant coatings, and desiccation. Penstocks are also used in mine tailings dam construction, the penstock is usually situated fairly close to the center of the tailings dam and built up using penstock rings, these penstock rings control the water level letting the slimes settle out of the water, this water is then piped back under the tailings dam back to the plant via a penstock pipeline. [edit] In watermills [edit] Similar structures Similar structures which are not enclosed are head races or leats (non elevated), and flumes (elevated). [edit] External links • Penstock cross-sections for the Grand Coulee Darn • J].S Department ofEnergv Hydropower Basics v_. ''4 This technology-related article is a stub. You can help Wikipedia by expanding it. Retrieved from "http;/ len. wiki12edia. org/wiki/Penstock" Categories: Aguedus;ts • Hvdroelectric power stations • Technology stub_~ Views • Article • Discussion • Edit thiUL~ • .History Personal tools • Lo!!l.nLc::reate account LARSEN BAY HYDRO-OPERATION AND MAINTENANCE PROCEDURES OPERATION PROCEDURES Project shut-down in event of sub-standard Operation The project shall remain in operation only when all project facilities are in good repair and functioning normally. Failure of certain components will result in automatic shutdown of the plant The operator must manually shut down project operations if and when equipment is in poor repair and failure may be imminent. Procedures-overview Currently, the plant is operated alone as an isochronous facility (Load Following control). Plant output is controlled by the city loadlgovemor, following the load of the city. The facility has never run in ?arallel with the city diesel plant. The city diesel plant is only turned on to allow the reservoir to refill when water supplies are limited. NOTE: At time of writing, head level indication is not available at the hydro due to a broken underground wire. As such, the Head Level control mode is not an approved operating mode. Operating the diesel and hydro separately is a much simpler way to operate and maintain the facility. The water level is monitored visually and all switching takes place manually. The output of the hydro fully meets the city load requirement. If the cannery comes on-line, and sufficient water is available, the hydro should be operated as a base load unit, Head Level or Auto Spear control, (Head Level control not available at time of writing), and the cannery should be responsible for managing the load swings at their facility (isochronous load control). As designed, the facility should be capable of normal, unmanned automatic operation serving the village power requirements alone or in parallel with existing diesel electric plants as required, however, current experience and plant configuration indicates that parallel isochronous operation of the hydro with City diesel is not a desired option. When paralleled with diesels, the hydro should be base loaded (Auto Spear or Head Level, see section 8 "On-line Operation with diesel"). Regardless of the mode of operation, all start-up, loading, operating, and shut-down of the facility must be coordinated with the cannery, the diesel plant, and end-users, if necessary. City of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 1 of 21 Operations Procedures are listed below for the various conditions that may be encountered, operating independently or in parallel with a diesel plant (design conditions only), are presented in the following sections: 1. Reservoir Filling and Draining 2. Penstock Filling and Draining 3. Hydro MMI overview screen 4. Start-up 5. synchronization and Loading 6. on-line operation General 7. on-line Operation-Hydro only 8. on-line Operation -with diesel 9. Plant shutdown City of Larsen B~y Hydro-Electric Facility Business Operating Plan 2 of 21 1. Reservoir filling-and draining. Filling Filling of the reservoir is accomplished by closing the 30-inch diameter Waterman gate valve at the dam site which closes the 30-inch diameter drain pipe. Prior to this closing, the 24-inch diameter Waterman penstock gate should be adjusted approximately 20 percent open (no more than eight complete turns of the valve handle) if simultaneous penstock filling is desired or closed completely if penstock filling is not desired. The normal reservoir operating level is 7.75 feet above the penstock invert (appropriately 3.0 feet on the staff gage) which is the elevation of the spillway. It is essential that the reservoir be flushed regularly (monthly) with a Fire Pump to clean out any rocks and debris that could damage the turbine or other equipment. This activity should be coordinated with the cannery, the diesel plant, and end-users if necessary. Draining The reservoir is nom1ally drained by opening the 30-inch diameter Watem1an valve at the dam site. Open the valve slowly to gradually establish an acceptable drainage flow. City of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 3 of 21 2. Penstock Filling and Draining Filling Prior to penstock filling, check the vent and air release valves to insure no obstmction exists, if possible. Filling of the penstock is accomplished by slowly opening the 24-inch diameter Waterman gate valve at the dam site which is connected to the 18-inch power penstock. Prior to opening, the butterfly "guard" valve in the powerhouse should be in the full open position and the turbine spear valves closed. If the spear valves are open, the hydraulic deflector should be fully closed to prevent turbine operation. The 24-inch gate valve should not be opened over four inches (no more than eight complete turns of the valve handle) until the penstock is fully watered. This will provide slow filling ofthe penstock and allow trapped air to be released by the three-inch penstock vent (at dam location) and the four air release valves located along the penstock. (Note: Vibration will occur if filled at a faster rate.) No penstock valve may be operated completely in less than 60 seconds; otherwise, penstock pressures or vacuum may cause penstock damage. · Draining Although a 3-inch penstock air vent is provided at the dam site to prevent a vacuum from forming during penstock drainage, safety dictates that the reservoir first be drained and the 24-inch diameter Waterman gate (penstock) valve be open prior to draining the penstock. This procedure provides additional protection against creation of a vacuum in the penstock with possible pipe collapse and damage. Normal drain sequence would be: 1. Shut hydro unit down, and ensure the unit indicates a green Disabled on the overview screen. 2. Open the 24-inch and 30-inch Waterman gate valves at dam site and drain reservoir. 3. Check the 24-inch penstock gate and the 3-inch vent pipe to insure no obstructions. 4. Open the powerhouse butterfly valve. 5. Manually open the spear valves by clicking on the turbine icon located on the overview screen, and selecting Manual on the spear control popup. The spears can be operated by clicking on the Open spears push button (spears in manual operating mode) to drain the penstock. Citvof Larsen Bay Hydro-Electric Facility Business Operating Plan 4 of 21 During emergency, such as penstock failure, the penstock can be drained by: 1. Close the penstock 24-inch diameter Waterman gate valve. 2. Check the 3-inch air vent for obstructions. 3. Open the powerhouse butterfly valve. Open the turbine spear valves. City of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 5 of 21 3 . Hydro MMI Overview Screen t.U - 04/25/03 10 :02 :49 LBH-U1 E-STOP PRESSED 04/25/03 10 :02:(9 LBR-GRID !'OVER HOT OK J t ..!;...Jl:.....:.·Cl H l.il • ~ :_~ -Z'oL ...!1..-·-d Gty of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 6 of 21 4. Start-up Prior to initiating start-up ofthe turbine generator, complete the following: a. Fill penstock and ensure that the 24 inch gate valve is open (at the dam site) and the powerhouse's butterfly valve is open. The reservoir should be at operating level. b. Check the 24-volt station batteries, which must be charged and connected to the control panel. c. The turbine spear valves and deflectors in fully-closed position (visual inspection of mechanical linkages on turbine). d. Governor resistor load banks and water storage tanks are full, water circulation (cooling) systems are operational and inlet/outlet valves are open. e. A visual check of the turbine, generator, related systems and tail race to ensure all systems are in good repair, clear of hazards or restrictions, and ready for nomtal operation. f. A visual check of the turbine generator bearing oil levels to ensure levels are normal and no water is in oil and ready for operation. g. Check and ensure that the main generator breaker is in open position and ascertain if the generator will be closing in on a "live" or "dead" bns. h. Examine the MMI Current Alarms screen and verify that all systems are normal and no alarms are present. Reset and clear all alam!S prior to starting. 1. Select desired operating mode and setpoints as outlined in following sections. Normal start-up is achieved by selecting the Enabled/Disabled control bar located below the turbine icon, and clicking on the Ena/Dis button located in the popup as shown below. This will toggle the control bar from a green Disabled to a red Enabled. At this point the operator can enter a kW setpoint or enable one of the control modes (Head Level control not available at time of writing). The PLC then automatically opens the deflectors, and slowly opens the spear valves and accelerates the turbine until it reaches normal speed and voltage. The unit is now under normal automatic control ofthe speed governor and the automatic voltage regulator. Breaker closure occurs automatically if operating \\1thin acceptable frequency and voltage (See Synchronization and Loading). City of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 7 of 21 Green generator = Breaker open and unit is ready to start Red generator = Breaker closed Blue generator (shown) =Problem or active alarm. Check the Unit Detail or Current Alarms screen for problem. Start-up -For Dead Bus operation Since the control screen (MMI) at the hydro requires AC power, an Uninterruptible Power Supply has been provide to allow the hydro to be used for restoring system power. (Load Follow mode should be selected). When UPS power is not available following a system outage, restoration of power should be accomplished with the city diesels. With normal system conditions supplied by the diesels, the hydro can be started and operated as outlined. Gty of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 8 of 21 5. synchronization and Loading 1. After selecting Enable of hydro unit, and subsequent valve opening, unit will automatically come up to rated speed and voltage and close the unit breaker when within acceptable voltage and frequency limits. The following should be verified: a. Verify the unit is running at synchronous speed (60Hz) and rated voltage ( 480 volts line to line). Verify that the sync accept white light is "on." b. Check head level to ensure adequate reservoir level at 7.75 ft normal. (About 3.0 feet or greater on the staff gage.) (Function not available at time of writing). c. For Load Following mode only, check the generator output power meter to ensure the desired amount (Load Follow.Setpoint) of generator output is being supplie~ to the resistor load banks and that the Silicone Controlled Rectifier (SCR) controls are properly operating (SCR red lights normal). (Note: the SCR controls the amount of power output to the load bank). d. Examine the MMI screen and verify that all systems are normal and no alarms are present. 2. Adjust machine frequency, if necessary, to match the line frequency (s:>mchronization). (Generator frequency is automatically controlled at 60Hz.) Match machine voltage to line voltage. a. Synchronization is verified by monitoring the frequency, voltmeters and synchro-lights. Adjust frequency to match line by pressing front panelloweriraise frequency buttons. Adjust machine voltage by turning front panel voltage adjust knob. Adjustments must be within normal operating limits (set points) of the frequency and voltage relays (check setting limits at project start-up). Limits to be marked on panel instruments and verified semi-annually. b. Upon closing into a running system, generator output loading will increase to Unit kW setpoint depending on mode of operation (auto spear, head level, load following), as more fully discussed in the "on-line operation" section of this plan. 6. on-line Operation -General During normal operation, plant output power (kW), frequency (Hz), and voltage is automatically controlled by the PLC, governor, and automatic voltage regulator. As discussed in this section, under design conditions, operations in parallel with the system diesel generators must be coordinated to ensure efficient output of the hydro plant and maintenance of acceptable system frequency and voltage. When the hydro plant is operated alone as the only system generator, system voltage and frequency "set points" can be adjusted by pressing the panel mounted frequency adjust push buttons and rotating the voltage adjustment knob. The governor control as manufactured will operate in the isochronous (Load Follow) mode; that is, the plant will attempt to maintain the system frequency at 60 Hz by automatically adjusting the plant output to match the system load requirements. Should the required system load exceed the plant capacity (475 kW) or available water, the system frequency will decline below ·60 Hz, and the plant will automatically shut down when the frequency reaches the under frequency relay trip point. Such automatic shutdown can be avoided by bringing additional diesel generators on-line with the hydro plant when excessive system loads are anticipated. Three modes of operation (Spear Valve, Head Level, Load Follow) are outlined as follows: spear valve operation -General The two spear valves control the water stream to the Pelton turbine wheel. Frequency is not controlled. Output of hydro must be maintained below available system load. Gtv of Larsen Bav Hydro-Electric F~ility Business Operating Plan Page 9 of 21 1. In the Manual Spear operation mode, the valves may be adjusted manually by either the Open and Close push button, or Spear Percent Open slider on the control screen popup. This option is not intended for normal operation and should only be utilized fo~ testing and maintenance activities (valve operating speed is not effected by operatmg mode). 2. In the Auto Spear operation mode, the operator may select a desired kW output setpoint by entering a Power Set Pt., or adjusting the kW Output slider. The spears are automatically adjusted open or closed to maintain the desired setpoint. 3. Spears must be in Auto control mode in order to enable Head Level or Load Following modes of operation. 4 . Spears can be individually Enabled/Disabled in this control screen (unit output may be limited). Head Level operation -General NOTE: At time of writing, head level indication is not available at the hydro due to a broken underground wire. As such, the Head Level control mode is not an approved operating mode. In the automatic Head Level control mode, the head level transducer at the dam informs the PLC of the head level, and the spears are adjusted open or closed to normally regulate a constant acceptable reservoir operating level. Frequency is not controlled. Gtyof Larsen Bay 1. Spear control must be in Auto. 2 . Head Level control is achieved by selecting the Enabled/Disabled control bar located on the Head Level/Reservoir icon, and clicking on the Ena/Dis button located in the popup as shown below. This will toggle the Head Level control bar from a green Disabled to a red Enabled. Hydro-Electric Facility Business Operating Plan Page 10 of 21 Load Following operation -General In Load Following control mode, the governor constantly adjusts the load bank to maintain 60Hz. The PLC adjusts the spears to maintain the desired amount ofkW on the load bank. Frequency is controlled. 1. Spear control must be in Auto. 2. Load Following control is achieved by selecting the Enabled/Disabled control bar located on the Head Level/Reservoir icon, and clicking on the Ena/Dis button located in the popup as shown below. This will toggle the Load Following control bar from a green Disabled to a red Enabled. 3. The PLC will control spear Open/Close to maintain the operator adjustable Load Follow Setpoi11t. Gty of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 11 of 21 OC/25,03 10:02:49 LBB-01 E-STOP PRESSED OC/2VOJ 10:02 :49 LBB-GRID PO'IlER NOT OK .:,·:~ +" r-; ''" -rqt U.J KtSUIDIIi 1'6' -gET ~\[a; Deflector operation -General The defectors are a small metal cup, which drops in front of the spear valves to direct water away from hitting the Pelton wheel and, thus, reduces power to the turbine/generator. The position of the deflectors are automatically controlled by the PLC and governor control module. There are no provisions for manual control of the deflectors. In normal automatic operation (Load Following) deflectors will only enter the stream intennittently as required to quickly reduce generation to control frequency. Following action of the deflectors, spear values are slowly closed automatically to allow removal of the in-stream deflectors and balancing ofload banks. During shutdown, hydraulic operating pressure to the deflectors is dropped and deflectors immediately fall into full stream, cutting off all hydraulic power to the water turbine. During start-up, hydraulic operator pressure is applied to the deflectors, which removes them from the water stream and allows the timed opening of the spear valves to slowly increase turbine speed. Load Bank Operation -General Gty of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 12 of 21 During startup and Load Following operation, the load bank is loaded to the operator defmed Load Follow Setpt. Instantaneous load swings are served by the releasing or adding of lolld to the bank. In this fashion, normal swings do not require constant or abrupt changes to the deflectors or spear valves. Important characteristics are: I. System load decreases below the available capacity of the load bank (operator defmed Load Pol/ow Setpt) will result in immediate deflector operation to regulate frequency. 2. System load increases beyond bank load (operator defmed Load Follow Setpt) cannot be served by the project due to the slow 60 second operating time of the spear valves. During such instances, system frequency will normally decay until the plant relays completely shut down the project. 3. The P4C monitors load changes and will adjust spear positions automatically in an attempt to keep load banks loaded at the.operator defmed Load Follow Setpt. 4 . Adjustment of the Load Follow Setpoint is simply made by clicking on the value box (as shown below) and entering a new number. Range of Load Follow Setpoint is lOkW (minimum) to 60kW (maximum). 5. Heat from the load bank needs to be monitored to prevent overheating the power plant. kW = Actual bank load+ Village load (Total generator output kW). kW Set Pt =Load Follow Set Pt +Village load. Load Follow Set Pt =Operator adjustable load bank setpoint. voltage control -General As designed, the hydro plant will automatically control the system voltage. The plant is presently operated in a voltage droop mode. Voltage droop maintains an acceptable voltage when supplying th~ village only• and allows operation in parallel with other diesel generators when supplying village and cannery loads simultaneously. Gty of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 13 of 21 7. on-line operation -Hydroelectric only-Load Follow Mode (Isochronous Load control) Nonnally the hydro project will be 'on line' serving the community, in automatic (Load Following) governor and voltage regulator operation. Should the system be initially under diesel plant operation, the hydro plant can be synchronized and closed to the system. With Load Follow mode enabled, the diesels can be taken off-line. Unloading of the City diesel units is accomplished by raising the frequency of the hydro project (press frequency increase button) until the diesel units are at minimal load. Opening ofthe City diesel breaker will then be automatic by reverse power relay operation of the diesel plant. As designed, the hydro plant should be capable of serving the electric needs of Larsen Bay without the assistance of diesel generators except during maintenance · or low water periods. The addition of new loads or starting of large motors may require parallel operation of diesel generation units. Operating experience is required to determine when diesel units are required. Assuming adequate stream flow, the project capacity of 475 kW is more than adequate to serve the estimated existing peak load of200 kW, and normal load swings should be easily served by the 120 kW load bank controlled by the electronic governor. System controls must be in automatic Load Following mode during normal operation. The project will normally control system frequency and voltage within the allowable tolerance of +2 Hertz. The Load Follow Setpoint should be set for maximum load fluctuation (or anticipated load increase/decrease). Using the available trending screens, the operator can determine the amount of abrupt load change (ie .. .less than 60 second change from steady load to a lower or higher load). For example: If the normal village load is 100kW with abrupt load changes to 115kW (or down to 85kW), the Load Follow Setpoint could be safely set at 20kW. This 20kW setpoint will allow an additional 5kW (in addition to the observed ·15kW load fluctuation) margin for any unforeseen load changes. Poor water periods or excessive loads may cause system frequency to drop, and result in automatic plant shutdown. Based upon operator judgment, hydro, diesel, or a combination of generation may be appropriate during such times. Generally, the hydro plant should be utilized at the highest allowable capacity during such periods to conserve diesel fuel. kW =Actual bank load+ Village load (Total generator output kW). kW Set Pt =Load Follow Set Pt +Village load. Load Follow Set Pt = Operator adjustable load bank setpoint. Adjustments to the spears are made by the PLC when (kW -kW Set Pt = ±10kW). In other words, when actual load on the bank is 1 OkW more or less than desired, the spears are adjusted to cause an increase or decrease on the load bank to bring it back within IOkW of desired setpoint. G.ty of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 14 of 21 8. on-line operation -with Diesel Generation -Auto Spear/Head Level (Base Load control) The facility has never run in parallel with the city diesel plant. These procedures are based on original plant design. Increased system loads such as cannery operation or poor water periods will require the hydro project to be operated normally in parallel with existing diesel generators. The number and capacity of required diesel units will depend upon operator monitoring of system loads and experience. Parallel operations of any and all plant combinations must be tested to assure correct setting of governor and regulator controls to prevent hunting or fighting between generation units. Initial testing and adjustments should be conducted only by qualified personnel approved by the owner. Periodic adjustments may be necessary. During the time that the cannery will be in operation, and there is an adequate supply of water, the hydro should be operated in base Head Level controL This mode will allow maximum use of available water and reduce diesel fuel costs. It is assumed that the system load during this time will be greater than the maximum 500kW output capability of the hydro. If system load decreases below output of hydro, the plant will shutdown on overfrequency. During times that the Cannery ice machine only is started {or any time a large motor is anticipated to start), the City diesels should be put on-line and the hydro switched to Auto Spear mode with a kW setpoint of approximately half of the system load prior to the ice machine starting. This configuration will help support large motor starting since the diesels are faster than the hydro in responding to a load increase. Once the motor load has started and is on-line, and the hydro is capable of supplying the new load, the hydro can be switched to Load Follow mode and the diesels can be taken off-line. Base Load control (Diesels controlling frequency) Normally the hydro project will be 'on line' serving the community in automatic (Load Following) governor and voltage regulator operation. Synchronize and close the required diesel generation units on line prior to occurrence of new load (such as cannery startup). Diesel generator governor controls should be adjusted to operate in "Isochronous" load control, and the hydro switched to Head Level mode or Auto Spear mode (with Power Set Pt. selected). NOTE: At time of writing, head level indication is not available at the hydro due to a broken underground wire. As such, the Head Level control mode is not an approved operating mode. 1. Head Level control will vary the hydro output depending on the available capacity of reservoir and stream flow. System load must remain above hydro output, and diesel generation must be capable of maintaining system frequency during load increase/decrease and/or hydro power increase/decrease. 2. Auto Spear control will maintain constant hydro output at the operator selected kW setpoint regardless of excess water availability or system frequency. System load must remain above hydro output, and diesel generation must be capable of maintaining system frequency during load increase/decrease. This is a desirable mode for operation of the hydro and City diesels when the system load approaches maximum diesel output and/or a large motor is known to be starting. (Any kW output set on the hydro will reduce diesel load by that same amount). voltage control Careful attention should be paid to matching system voltage when bringing on parallel diesel generation. If system voltage is high/low prior to synchronizing the cannery diesels, then the hydro voltage should be decreased/increased to an acceptable level for the cannery to come online. If, on the other hand, the cannery synchronizes to a lower than desired voltage and then raises their diesel voltage to compensate, the hydro will absorb an excessive amount of Vars. Citv of Larsen Bav Hydro-Electric F~i1ity Business Operating Plan Page 15 of 2l I i Raising or Lowering of system voltage should be coordinated between hydro and cannery to avoid excessive Var flow between generators. If it is determined that the system voltage is low/high, the cannery and hydro voltages should both be raised/lowered. Raising or lowering of a single generator, and not the other, will primarily result in excessive current!V ar flow between generators. Generator (cannery and hydro) Var output should be monitored during synchronization or adjustment After diesel generators and load are brought online, an attempt should be made to proportionally balance the Var load between cannery and hydro. Once the Var load is balanced between hydro and diesels, proportional Var sharing should be automatically maintained. Daily monitoring of hydro Var load is recommended for efficient operation. 'n1e following chart summarizes operating modes for both hydro and diesels: HYDRO HYDRO AND Qry DIESEL ONLY Mode of Hydro Hydro Operation Isochronous (Load Yes No Following) Base Load- (Auto Spear No Yes Control) Base Load Not (Head Level tested Not tested and and approved Control) approved City of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 16 of 21 Oiesel Yes No N/A HYDRO AND C'..ANNE~ DIESEL l Hydro Cannery Diesel ! No Yes ' ' Yes :\o Not tested and N!A approved i l I 9. Plant shutdown The following will automatically cause plant shutdown and the MMI Alarm message will signal appropriate cause: a. Over or under frequency conditions (check relay for settings) Check for low water, large motor starts, or improper control mode. b. Overvoltage (check relay for settings) Check for failed Voltage regulator or fuses. c. Undervoltage Check for failed Voltage regulator or fuses. d. Generator ground fault . Check for phase to ground fault from generator to step-up transformer. e. High load bank tank temperature Check for failed water pump, thermostat, or plugged screen or pipe. f. Low tank water level Check for failed water pump, plugged screen or pipe, or stuck float. g. High generator winding temperature Check for overloaded operation. h. High generator bearing temperature Check lube level or for bearing failure. 1. Reverse power (25kW into plant) Check for low water, improper control mode, or normal shutd0'-"'11 via diesel plant. J. High voltage ground fault Check for phase to ground fault on high side of step-up transformer and system. k. Reservoir Low Level l. Fail to Start Check for abnormal system frequency and voltage, fuse failure, auto-sync failure. m. Shutdo'-"'11 Fail Check for fuse failure, breaker failure. n. Main breaker opening Check for breaker failure, Overcurrent condition. o. Stop pushbutton Panel mounted stop pushbutton activated. p. System power not ok 480 Volt system out of tolerances. q. Low24VDC Check battery charger. Gtv of Larsen B av Hydro-Electric F~cility Business Operating Plan Page 17 of 21 Current alarms are shown on the Current Alarm screen as shown below. Only alarms that are still active (present) are displayed. Alarms are acknowledged by depressing the keyboard "space bar". 04/25/03 1 -U1 04/25/03 10 02 49 LBH -WATER TANK LOW LEVE L 04/25/03 10 02 49 LBH -U1 GROUND FAULT 04/25/03 10 02 49 LBH -WATER TANK HI TEMP 04/25/03 10 02 49 LBH -U1 OFFLINE 04/25/03 10 02 49 LBH -U1 E-STOP PRESSED 04/25/03 10 02 49 LBH -GRID POWER NOT OK 04/25/03 10 02 49 LBH -U1 RESERVOIR LOW LEVEL SHUTDOWN Red Alarm = Unacknowledged. Black Alarm = Acknowledged. LBH--"'·""'' -~<cM••u u <J o LBH--ALARM-ALMI0004 LBH--ALARM-ALMIOOOS LBH--ALARM-ALMI0006 LBH--ALARM-ALMN0007 LBH--ALARM-ALMN0010 LBH--ALARM-ALMN001 2 LBH--ALARM-ALM#0013 Previous alarms are shown on the Historical Alarm screen as shown below: Gty of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 18 of 21 041'251'03 10:02:49 ALM LBH -U1 LOW VOLTAGE 04/251'03 10:02:49 ALM LBH-WATER TAilK LOW LEVEL 0~1'251'03 10 :02:49 ALM LBH -U1 GROUND FAULT 041'251'03 10:02:49 ALM LBH -WATER TANK HI TEMP 041'251'03 10:02:49 ALM LBH-U1 OFFLINE 041'25.103 10:02:49 ALM LBH -U1 E-STOP PRESSED 0~/251'03 10:02:49 ALM LBH -ORID POWER NOT OK 0~1'25/03 10:02:49 ALM LBH -U1 RESERVOIR LOW LEVEL SHUTDOWN 04/251'03 10:02:51 ACK LBH -U1 RESERVOIR LOW LEVEL SHUTDOWN 04/251'03 10:02:51 ACK LBH -ORID POWER NOT OK 0~/251'03 10:02:51 ACK LBH -U1 E-STOP PRESSED 0~/25/03 10:02:51 ACK LBH -U1 OFFLINE 0~/251'03 10:02:51 ACK LBH -WATER TANK HI TEMP 041'25/03 10:02:51 ACK LBH -U1 GROUND FAULT 0~/251'03 10:02:51 ACK LBH -WATER TANK LOW LEVEL 041'251'03 10:02:51 ACK LBH -U1 LOW VOLTAGE Red = Time/Date alarm occurred. Black = Time/Date alarm was acknowledged. White = Time/Date alarm returned to normal. LBH--ALARH-ALM#0003 LBH--ALARH-ALM#0004 LBH--ALARH-ALM#0005 LBH--ALARH-ALM#0006 LBH--ALARH-ALMI0007 LBH--ALARH-ALM#0010 LBH--ALARH-ALMI0012 LBH--ALARH-ALM#0013 LBH--ALARH-ALHI0013 LBH--ALARH-ALM#0012 LBH--ALARH-ALM#~10 LBH--ALARH-ALHI0007 LBH--ALARH-ALMI0006 LBH--ALARH-ALMI0005 LBH--ALARM -ALH#O 00 4 LBH--ALARH-ALHI0003 The Unit Detail screen also shows alarms and other information as shown below. G.ty of Larsen Bay Hydro-Electric Facility Business Operating Plan Page 19 of 21 • 04/25/03 10 :02 :49 LBH-U1 E-STOP PRESSED I Ot/25/03 10:02: U LBH -GRID POVER HOT OK . J. J u.-l """'" .. -d t e.&:Z1f -, Automatic shutdown From Head Level mode: Disabling Head Level and entering 0 in the kW setpoint box will initiate a smooth plant shutdown . The PLC will automatically slowly close the spear valves and reduce generator output until it reaches a predefmed kW setpoint (lOkW) where the breaker will automatically open and shutdown. From Auto Spear mode: Simply enter 0 in the kW setpoint box and the unit will shutdown as described above. Manual Shutdown From Load Follow mode: Manual plant shutdown can occur by synchronizing and closing a diesel generator and slowly increasing its speed control until the hydro plant opens its 480V breaker and shuts down on reverse power (approximately 25kW into hydro plant). At that point, the diesel speed control should be returned to 60Hz. If no other units are online and a system outage is desired, the hydro plant can be shutdown by selecting th~ Enabled/Disabled control bar located below the turbine icon, and clicking on the Ena!Dis button located in the popup. This will toggle the control bar from a red Enabled to a green Disabled. The plant will immediately open the breaker and shutdown as outlined below in "Emergency Shutdown Sequence/Activities. (Pushing the panel mounted Stop button will accomplish the same). Gty of Larsen Bay Ii}Urc:rElectric Facility Business Operating Plan Page 20 of 21 · - Emergency shutdown sequence/Activities Alarm shutdown or pressing the stop push button will result in the following actions in rough descending sequences: a. Loss of deflector hydraulic operating pressure and fast closing of deflectors (complete closing). b. Opening of main 480V plant circuit breaker. c. Slow closing of spear needles until penstock flow has been stopped. Manual closing of the spear valves will result in automatic shutdov.n once under voltage/frequency trip points are reached. Citv of Larsen Bav H:r.dro-Electric F;cility Business Operating Plan Page 21 of 21 :merator syncnromzauon ~ Jum 1 u~ .1-\llllv••u 1 dex Home About rom: Neon John <johngdNOSPAM@bellsouth.net> ubject: Re: Linking 2 generators .. -ll'ri, 12 May 2000 11:40:18 EDT b. ~~-oups: reci.outdoors.rv-travel im Pattison wrote: For "fun" sometime, try parallelling two generators that are out of phase. They WILL get themselves in phase very quickly. The stress on the prime mover/drive train is something else. The key here is having a phase meter and then the necessary hardware to quickly bring one generator into a live circuit. Then ther is the little problem of keeping the load balanced so one generator doesn't try to take the entire load, and so on. ~ usual, a whole thread of people posting who don't know the answer tnd instead scold the guy for asking. ~ill, here's how it's done. l'wo AC generators operated in parallel must be not only at the same speed but also the same phase to be paralleled. Doing so it not at :tll difficult but you do have to know what you're doing. If the 1eutrals are connected together and then the voltage between the hot legs of the two generators is measured (hot leg to hot leg and not hot to ground), the following conditions will be noted: In phase: zero volts 1r --~grees out of phase: the sum of the two voltages. Since the v, ges must be the same, this will be 2X the nameplate voltage. The generators can only be connected together when the voltage between the hots is zero, e.g. in phase. This suggests a phasing method. The standard power plant method of synchronizing two generators is to use a very expensive instrument called a synchroscope. This instrument indicates whether the incoming generator is faster, slower or in phase with the bus. since the rotors of power plant generators weighs many tons, the phases must be extremely accurately matched or else the rotor will be forcibly yanked into phase, possibly wrecking the generator. For small units, we don't need to be so precise. We can use a pair of lamps. What you'll need is a couple of lamps hooked in series and connected between the hot lead of the running generator and the hot lead of the newly cranked generator. You'll also need a switch of some sorts to parallel the units. If the generators are 180 deg out of phase, the voltage across the lamps will be 2X the nameplate voltage (240 volts in the case of two 120 volt generators.) and the lamps will burn full brilliance. If the generators are nearly in phase, the lamps will be out because there will be no voltage on them. If one generator is faster than the other, the lamps will flicker on and off as the gens are in phase one moment and out the next. \ ;rocedure is as follows. Start the second generator. The lights will be flickering or slowly coming on and off. Manipulate file://E:\Generatoro/020synchronization%20(John%20De%20Armond).htm . -;.:::~-. -· - [iJ ActiO! Internet Explor The page migh· Please try the f • Click th· • If you h what hc: clickW1 • For info click thE Internet Explor 10/2/2008 ,1::1 Jt::J dlUI ;:)JII\...111 Ullll..CiliUII \VVIIII Llv <"\1111 ...... 11'-'/ .he throttle of the incoming generator which ever direction is tecessary to slow the flickering. As the speeds become almost !qual, the lamps will stay off for a long of time and then :lowly start lighting, slowly fully bright and then slowly dim • ~in. You want to manipulate the throttle until the lamps are off ;as long as possible. You want to close the breaker when the roltage between the generator is the least. Since the lamps will go )Ut before the voltage reaches ze~o, you'll want to mentally time :he period between going out and coming back on again and close the 5Witch about in the middle. )nee the breaker is closed, the are locked together. [ndeed, you could close the throttle of one engine and the coupled ~enerator will motor the engine at precisely the sync speed (3600 RPM for small gens). If the generators are just a little bit out of phase, then will be yanked into phase as momentary heavy ~urrent flows between them. And if you close it out of phase, then you have a double voltage short circuit. Usually there is severe mechanical and electrical damage. (I heard and saw the results of a 50 MW diesel genset being synched 180 degrees out as the result of reversed leads on the synchroscope. Literally ripped the stator out of the foundatlon and twisted the shaft.) Once the generators are in parallel, the load accepted by each generator is governed by the governor The generator with the most throttle will the most load. On larger generators, the field excitation is manipulated to control VARs but you don't have that control and so you have to accept what you get. Actually, the idea of more than one generator is very good lf you only occasionally have a heavy load to drive. If you bought a gp~erator large enough to run this occasional load, then most of the \ ! it would be running very lightly loaded and thus very inefficiently. Cranking the second generator for only those occasions when the large load is needed is a good solution. Here are some problems you may encounter: * Unequal voltages This will cause heavy circulating current to flow between the generators. Will cause overheating and excessive load on one or both generators. * Unequal voltage slope better than the other. one generator regulates voltage vs load Same result as above but varies with load. Can fool you into thinking the generators aren't "putting out" enough. * Unstable voltage regulation for generators that use electronic voltage regulation (most any brushless design}, you may find that the regulator cannot handle the new dynamics and either malfunctions or oscillates. This can damage the control, the field windings and the other generator. * One generator faltering -if one engine falters out of gas or low oil cutoff its alternator will motor the engine in order to preserve the lock. This will probably burn out one or both generators and if the engine is low on oil, damage the engine too. This is protected against in larger installations with reverse cu~rent relaying. Fairly inexpensive solid state relaying is !lable (TlmeMark Inc and other mfrs) but you do need to be aware o~ the need to use them. file://E:\Generator%20synchronization%20(John%20De%20Armond).htm 10/2/2008 INTRODUCTION AND PURPOSE General Guide This bulletin summarizes current policies for power operations and maintenance improvement. Effectiveness of the improvement program should constantly be evaluated and substantial modifications of the material given here can occur. Consequently, information in this bulletin is to be considered as a general rule and may be superseded by subsequent correspondence and supplemented by individual project needs. Need for Incident-free Performance The modernization programs and applications of new technology has produced significant changes in operational modes and increased complexity of systems. With emphasis on automation and remote control, personnel are experiencing less direct contact with equipment and are becoming less familiar with its operation. Unfamiliarity and reduced contact creates greater potential for misoperation of equipment. Consequences of misoperation or misuses are now multiplied due to expanded systems interconnections and increased public scrutiny of mistakes. One small mistake by an individual may have impact on electlical service in several states. Program Objective Experience has shown that a percentage of system outages have been the result of human incident. Since the consequences of these incidents can be very costly either in terms of equipment damage, lost revenue, or jeopardy to life and property, it is necessary to place emphasis on a program to eliminate or reduce all incidents. The objective of this program is incident-free performance throughout the Bureau of Reclamation through adequate training, improved communications, and adequate facilities. Attaining Incident-free Performance It is recognized that in systems as large and complex as today's water and power facilities, it may not be realistic to expect that all O&M incidents can be eliminated. However, by using incident-free performance as a goal, and every incident demonstrating the need for a solution to a problem, and by diligent pursuit of these solutions, the frequency of incidents can be reduced. It has been possible in given areas to attain incident-free performance over prolonged periods. A very practical objective is to attain incident-free performance for the day at hand and to plan for incident-free performance the next day. In this way, a long record of outstanding performance can be attained. Primary factors involved in attaining incident-free performance include: {1) an effective review whereby results are evaluated and incidents discussed; (2) adequacy of facilities and active pursuit of needed corrective measures; (3) adequacy of operating instructions; (4) an active training program for O&M personnel; (5) individual motivation to give required thought, care, and action; and (6) improved design process which could eliminate equipment or procedural deficiencies prior to O&M activities. Implementation of Program The individual effortofevery·memberofthe O&M team is required to insure successful implementation of the operations improvement program. This bulletin is intended to briefly discuss the essentials of the most important facets and to guide individual initiative. REVIEW OF ADEQUACY OF FACILITIES Objectives This review should be carried out with three major objectives: (1) to locate and eliminate, if possible, all potential "trigger" or "operating booby trap" situations which could initiate equipment outage or endanger personnel; (2) to modify facility designs and/or operating procedures to prevent or minimize outages; and {3) to develop operating procedures for reliable communication which will expedite the restoration of normal service should a misoperation occur. Items For Review of Facilities Continuing reviews of adequacy of system equipment by O&M personnel should include the following items: 1. Adequacy of emergency preparedness procedures. 2. Review of plans and procedures to be implemented upon the occurrence of an event with environmental impact. (Oil spill, chemical contamination, PCB spill, etc.) 3. Actual relay settings for primary and backup relays to determine whether field settings agree with current records and if any temporary changes have been 2 made that require future action or whether new settings should be made in view of changed conditions. 4. Operators' instructions for procedures to be followed during emergencies. Such emergencies include loss of major generating units, power system disturbances, and incorrect functioning of any one or series of protective relays. 5. Underfrequency load-shedding or separation schemes. 6. Procedures for system restoration plan. 7. Adequacy of communications and accuracy of telemetered information during system outage conditions involving high or low frequency, abnormal voltage, and other unusual conditions. 8. Adequacy of station service power supply immediately after a major shutdown and for subsequent startup. Need for additional sources of emergency station- service supply and/or changes in circuit design to provide remote indication of critical equipment (such as breaker position) during outages. Black start: (a) requirement, (b) capability and (c) procedures. 9. Governor action and effect of droop setting following load rejection with respect to hunting and frequency control. Causes of abnormal consumption of the energy in governor oil tanks. 1 0. Review of performance of supervisory control and data acquisition (SCADA or PMSC) systems during system disturbance. 11 . With increasing complexity of control equipment and diverse modes of operation of this equipment, it is more important than ever that standard nameplates for relaying, control, and switch identification be adhered to at all stations. Also, arrangement of devices on the control board to conform to standard arrangements shown by standard drawings prepared in the Denver office should be adhered to insofar as possible. Standard drawings are available for typical control board panels, such as for generators and other major equipment {see appendix A). A periodic review of existing nameplates should be conducted to ensure that: a. Nameplates are located so that they are readily visible and so that each nameplate will identify the· item of equipment for which it is intended without any doubt. •· b. Nameplate engraving with high contrast and location are consistent for similar equipment. 3 c. Control switch operation and escutcheon engraving are consistent for similar equipment. d. Normal lighting adequately illuminates nameplates. ·e. In locations where permanent emergency lighting has not been provided and it is a critical piece of equipment, provision should be made for portable emergency lighting and proper maintenance procedures. f. Nameplates, switch escutcheons, and mimic buses conform to standard drawings. REVIEW OF ADEQUACY OF OPERA llNG INSTRUCTIONS SOP'S (Standing Operating Procedures} To minimize incidents, it is necessary to initiate and sustain a program at all projects having power facilities to periodically review and update SOP's for each major facility. The Regional Director's authority in this program emphasizes the importance of such action, and this support is shown by his annual certification (approval) of operating instructions for each facility in that Region. Copies of certified operating procedures are kept at the appropriate installation for reference, training, and use during emergencies, A copy is kept in the project and/or regional office for review of adequacy and up-to-date status of instructions, and in the Division of Engineering, D- 8450, Denver, for review of program implementation. Contents of SOP'S SOP's are based on DOC's (Designers' Operating Criteria prepared in Denver), manufacturers' literature, engineering drawings, and regional and project procedures. They should include, among other items, instruction as to relays which must be blocked or removed from service while performing switching, sequence of switching operations, use of alternate communication facilities, information on operation of major equipment, etc. For SOP outline and preparation refer to "Power Facilities Supplement for Guide for Preparation of Standing Operating Procedures for Bureau of Reclamation Dams and Reservoirs." Copies of this publication are available from Project Operation Services Staff, D-5140. 4 OPERATIONS IMPROVEMENT PROGRAM Region. __ _ Project _______________ _ Work Team __________ Date of Class ______ _ From To ___ Hours ____ MeetingPiace ____ _ Instructor _______ _ Title __________ _ Personnel Attending: ENTER UNDER APPROPRIATE HEADINGS SPECIFIC ITEMS COVERED 1. Safe Clearance Procedures. --------------- 2. Standing Operating Procedures. -------------- 3. Switching Instructions. ----------------- Figure 2.-Training report. 12 4. Operations Improvement Reports. -------------- 5. Incident/Miscue Review. ------------------ 6. Unscheduled Outages and/or Emergency Conditions. _______ _ 7. Instructions Presented on Matters Covered Other Than Above. ___ _ 8. Remarks. ------------------------- Figure 2. -Training Report, Continued 13 OPERATIONS IMPROVEMENT REPORTING SYSTEM Purpose of Reporting Station inspections, routine operation and maintenance functions, and operating incidents ranging from incidents to near misses may all disclose a need for improvement in operating and maintenance practices or equipment installation and/or design practices. Also exceptional performance or recognition of an imminent problem in the operations arena should be documented and circulated if other Reclamation projects can benefit from the information (see figure 3 ). The purpose of this program is to allow the entire Reclamation to benefit from the experiences and expertise of each project. Distribution of the information received in this SYS!tem to the appropriate operations and/or design organizations will result in a safer and more efficient operation of Reclamation's facilities. Reports The Special Recognition report (see fig. 3) should be filled out and transmitted to ( 1) provide recognition for a special act, process, or procedures and (2) allow the benefits ofthe idea to be shared by all Reclamation facilities. The Incident/Miscue reports shall be submitted on Form PO&M 171, "O&M Improvement Reporting System," to the Division of Engineering, Code D-5200, Denver Office, with a copy to the appropriate regional director (see fig. 4 ). The reports should contain sufficient detail to permit an understanding of the problem encountered and any recommended solutions for it, but should not contain confidential detailed information regarding operating incidents (such as names, locations, and equipment numbers). Distribution of PO&M-171 is optional and should be completed if it is felt that the incident provides benefits to other projects or has significant local consequences. Use of O&M Improvement Reports O&M Improvement Reports may indicate the need for: 1. Changes in operations or maintenance procedures 2. Further training of personnel 3. Changes in design practices 4. Changes in installation procedures 18 The reports should be used to identify problem areas, determine constructive solutions, and to inform other who may encounter similar problems. The Division of Engineering will distribute the information from the reports to the appropriate offices in Redamation and will also prepare an annual summary of the reports. 19 .-~- EMPLOYEE INCIDENTS Purpose of Reporting Every incident or miscue indicates a need for improvement in some respect. To promote improvement in operations and maintenance procedures, each incident must be reviewed and reports prepared. To profit from such experiences, it is necessary to analyze existing problems and study recommended solutions. Written reports are intended for this purpose. Definitions of Employee Incident It is essential that the definitions of incidents be sufficiently clear to permit meaningful analysis of problems. The use of standard definitions will promote uniformity and minimize inequities among regions. Toward that end, the definitions on PO&M-171 have been developed. Formation of Review Boards In cases of major incident involving personal injury, loss of life, serious damage to equipment or major system breakup, a review board shall be appointed by the Regional Director or higher authority and shall include a member from the Division of Engineering, D-5200, Denver Office. In all other cases, it is recommended that a project-appointed review board of one to three members conduct the investigation and write the reports, including statements covering actions already taken or recommended that will aid in preventing similar recurrences. In the case of incidents of a minor nature, it may be more effective if the project-appointed review board consists of local participants such as the plant superintendent, foremen, and co- workers of the individual involved in the error. Project safety and personnel staff members should be used as required in an ad hoc advisory capacity. Need For Prompt Attention It is essential that all incidents/miscues receive prompt attention, action, and response by the review board. The action taken on the incident by the review board should be made available to all personnel involved as quickly as possible. Swift review promotes better understanding by the review board members of the circumstances surrounding the incident and leads more directly to the cause and solution. 21 Reports Two reports are to be prepared. 1. A detailed report giving all pertinent information for confidential use with in the project or region. Each responsible project or office shall maintain a complete file of detailed reports for review by the region and D-5200. 2. An Operations Improvement Report (Form PO&M-171) for submission to the Division of Engineering, Denver Office, D-5200. The report is for the annual summary and provides an overview of the effectiveness of the program Bureau-wide. This report shall also be distributed Bureau-wide when other facilities will benefit of has significant consequences. lncidentfmiscue reports for internal project or regional use should contain sufficient detail for effective follow through by management. The suggested format is shown in figure 5. Much attention should be given to items 4C and 4D, concerning cause and solution-steps taken to improve the reliability of electric service. The operations improvement reports will be used by the Division of Engineering, D-5200, Denver Office, to prepare periodic reports for Bureau-wide distribution. Safety Reporting All incidents resulting in property damage or personal injury shall be reported in accordance with standard safety reporting procedures as set forth in chapter 4, part 365, of Reclamation Instructions, series 350. The report of the review board prepared for internal project or regional use should accompany the accident report and may be used in lieu of the required narrative. MOTIVATION FOR INCIDENT-FREE PERFORMANCE Recognition of Outstanding Performance The preparation, thought, and diligence in performing O&M action required for incident-free performance for a sustained period of time do not come easily. Much effort is required for their attainment. Perhaps the most effective motivation of employees to do a good job is the sense of satisfaction gained in the knowledge they are doing a good job. Inherent in this is knowledge that the group's (or individual's) supervisors recognize that a good job is being done. Individuals or groups that have demonstrated outstanding work under recognized conditions of exposure should be recognized or 22 SUGGESTED FORMAT FOR DETAILED REPORT ON EMPLOYEE INCIDENTS (Confidential Internal Use Only) 1. Heading on Report The heading of the report shall incorporate in the following order: (a) The reference, "Employee Incident." (b) The name of the region, project, and station involved. (c) The name, job title, and grade of personnel involved. (d) The date of the occurrence. (e) Incident definition, from PO&M-171. 2. DESCRIPTION OF OCCURRENCE Give as concisely as possible in the order undernoted a comprehensive description of the occurrence. Include all relevant information which would assist in conveying a clear understanding of what took place and the reasons for it, or which would be helpful in arriving at a judgment of the correctness of the conduct of the parties concerned. A statement such as: Inattention to job at hand, is not sufficient. (a) Events leading up to the occurrence, with remarks on time available, stress, disturbing, or distracting factors. (b) The fault occurrence. (c) The results, injuries, damage, service impairment. (d) The restoration of service. (e) Supplementary diagrams and sketches as required. 3. TITLES AND DUTIES Indicate the titles and duties of the parties directly involved: (a) Normal duties. (b) Special duties, if there was any departure from the normal during the period under consideration. 4. BOARD OF REVIEW ANALYSIS AND RECOMMENDATIONS (a) Reduce the incident to the simplest possible statement of what took place from a point of view of conduct, especially commendable. (b) Comment on the correctness of conduct and the degree thereof, and mention any extenuating circumstances. (c) Indicate briefly the factors that would best summarize the incident as to cause. Attempt to answer such questions as: Incident in judgment? Failure to communicate?. Better or more extensive training needed? Management action needed? Inadequate facilities? Manufacturer/Design/Construction involvement? (d) ~tate corrective actions recommended in light of the causes identified in 4(c) above. (Be specific.) Figure 5. -Suggested format for detailed report on employee incident. 27 Larson Bay Hydro DAILY MAINTENANCE AND INSPECTION REPORT Date Time Operator Name Instructions: Initial and note time/date each item last completed or other action. Send Daily and Monthly Reports to: Art Copoulos A IDEA 813 West Northern Lights Blvd. Anchorage, AK 99503 (or fax:907-269-3044) Output Meter Reading KW KW hours TURBINE Bearings Oil Level Visual Inspection I Nozzles: ------- Drive Side -------Oil Added ______ _ Heat ______ _ Clean cooling water strainers: Alarms Checked GENERATOR Temperature: CHECK CONDITION OF: Drive S1de ------- Volts: Reser.;oir Level _______ _ Non-Drive Side _______ _ Oil Added _______ _ Heat _______ _ Non-Drive Side _______ _ Between Oct 15th through April 15th Inspect Daily Dam --------------------------------Air Snow & Ice --------------------------------Gate Valve ---------------------------------- Reservoir Elevation Est. Dam Leakage _______ _ COMMENTS I Problems I Activities I Damage Larson Bay Hydro MONTHLY MAINTENANCE AND INSPECTION REPORT Date Time Operator Name Instructions: Initial and note time/date each item last completed or other action. Send Daily and Monthly Reports to: Art Copoulos A IDEA 813 West Northern Lights Blvd. Anchorage, AK 99503 (or fax:907 -269-3044) Oil Deflector Cylinder Rod---------------- Oil Deflector Pivot Points ----------------- Check Condition of Batteries --------------------------Action Taken ------------------------------ Clean Powerhouse: Wipe Down Turbine _____ _ Wipe Down Generator _____ __ Grease Generator (every 6 months): Drain and Flush Reservoir and install sump in front· of intake: -coordinate with Cannery and Diesel Plant Sweep Floor _________ _ Empty Garbage _________ _ Complete infrared inspection of swithgear (once/year) ---------- Inspect breaker contacts, grease hardware, arc shutes, etc.(once/5 yrs.) Clean/Check Bus Work connections, tightness, signs of overheating (once/5 yrs.) Calibration of system relays, meters, and transducers (once/2 years) Replace PLC and MMI Uninterruptable Power Supply (UPS) (oncel5 years) COMMENTS I Problems I Activities I Damage I Maintenance Recommondations: / [ / POWER SYSTEM CLEARANCE PROCEDURE January 1989 Western Area Power Administration Power System Operations Manual Chapter 1 Bureau of Reclamation F acilities/lnstructions/Standards{f echniques FIST Volume 1-1 United States Department or Energy Western Area Power Administration Golden, Colorado United States Department of Interior Bureau of Reclamation Denver, Colonldo • J CONTENTS Page Preface ....................................................................... . Section I. Introduction ................................................................ 1 II. Definitions ............................... , ................................... 4 Ill. General responsibility and authority ........................... 9 IV. Materials for use with these procedures and instructions ........................................................ 11 V. Clearances ............................................................... 25 VI. Hot Line Orders ........................................................ 36 VII. Special Condition ..................................................... 42 VIII. Danger Tags ............................................................. 43 IX. Tagging of equipment operated by supervisory control ............................................. .45 X. General Switching ................................................... .46 XI. Operations associated with contractors or non-Agency forces ........................... .47 XII. Operations associated with non-Agency maintenance forces .............................. 51 XIII. Operations associated with Interconnected Systems ........................................... 53 XIV. Instructions for Power System Switching ................. 57 XV. Index ......................................................................... 61 FIGURES FIGURE Page 1-. Switching Program Form .......................................... 14 2. Switching Order ........................................................ 15 3. Safety Tag ................................................................ 19 4. Hot Line Tag ............................................................. 20 5. Special Condition Tag .............................................. 21 6. Supervisory Control Tag ........................................... 22 7. Danger Tag ............................................................... 23 8. Special Work Permit.. ............................................... 24 I. INTRODUCTION 1.1. PURPOSE. The purpose of this Document is to establish coordinated and consistent procedures and operating criteria for the safe and reliable operation and m-aintenance of those facilities of the Federal power and water system for which the Bureau of Reclamation (Reclamation} and the Western Area Power Administration (Western) are responsible. These procedures and operating criteria include Clearances (Section V), Hot Line Orders (S.ection VI), Special Conditions (Section VII), Danger Tags (Section VIII), General Switching (Section X), and Special Work Permits (Section XI). 1.2. SCOPE. This Document establishes procedures and operating criteria which shall be complied with throughout Reclamation and Western. It is recognized that it may be necessary for Western/Reclamation to develop specific written Regional/Area or Project procedures within the requirements of this Document. It is further recognized that it may be necessary to jointly develop specific procedures at the Region/Area level in order to implement the require- ments of this Document. Any Regional/Area procedures developed to implement these procedures and operating criteria shall be at least as strict as the requirements of this Document. 1.3. REFERENCES. • Reclamation Instruction Series 250, "Power Operation and Maintenance." • Section 302 of Public Law 95-91, the Department of Energy Organization Act, dated August 4, 1977. • Agreement on Transfer of Facilities Between Water and Power Resources Service (currently the Bureau of Reclamation) and Western Area Power Administration, dated March 26, 1980. 1 1.4. REVIEW AND REVISION. This Document will be reviewed annually by both Reclamation and Western to assure that the guides and procedures herein are adequate for the safe and reliable operation and maintenance of the Federal power and water system. Proposed revisions will be jointly reviewed and agreed upon prior to publishing and implementing a revised Document. Regional/ Area proce- dures will be reviewed annually to assure conformity with this Document. 1.5. INTERPRETATIONS. The stated interpretations for the following words shall be applied throughout this Document: • "May~' -Permissive choice • "Musf' -Mandatory • ~~shall" -Mandatory • "Should" • Advisory • tfWill" -Mandatory, but allowing the responsible employee or party some discretion as to when, where, and how. • As used in this Document the pronouns "He," "His," and "Himself" refer to a specific individual or position, which might be "She," "Her," or "Herself" in a given circumstance. Also used in this context are the terms "Foreman," "Lineman," lfSwitchman," and nworkman." 1.6. EMERGENCIES. In an emergency, Authorized Personnel may modify or suspend any of these guides temporarily as may be considered necessary to permit proper handling of the specific emergency. However, in handling such emergencies, safety of personnel shall be given paramount consideration. 1.7. PHILOSOPHY OF CLEARANCE PROCEDURES. The following principles, whether or not they are specifically addressed in this Document. are considered basic to the safe operation of the Federal power and water system: 2 1.7.1. The priorities involved in applying clearance procedures are: a. Physical safety of employees and the public. b. Integrity and reliability of the Federal power and water system. c. Protection of equipment. d. Service to the customer. 1.7.2. Clearance Tags, Hot Line Order Tags, Special · Work Permits, and Danger Tags are applied to protect people; Special Conditions are applied to protect equipment and/or the Federal power and water system. 1.7.3. Throughout Reclamation and Western, all activities such as placement, issuance, receipt, release, and removal of all switching programs and associated operations are to be performed by Authorized Personnel, except in emergencies as provided for in paragraph 3.3. 1.7.4. All switching operations shall be guided and tested by the fundamental principle, "Start with the correct procedure and follow it exactly," and can best be accomplished by following: THE SIX BASIC STEPS OF SWITCHING 1. Carry the switching program with you while switching. 2. Touch or point to the device identification nameplate to verify it's/your location. 3. Recheck the switching program for right location and right sequence. 4. Verify anticipated device position. 3 5. Perform requested action on the device. 6. Verify desired device position. 1.7 .5. Employees shall be indoctrinated to realize, "If I violate this Safety Tag, Hot Line Tag, or Danger Tag, I may kill somebody!" 1.7.6. Safety, Hot Line, and Danger Tags are to be considered the same as a lock. The tagged equipment shall not be operated when one of these tags are in place on the control device for that equipment. 1.7.7. A basic principle pertaining to Federal power and water system operation is that the lengths of time the equipment is abnormal or removed from service for any reason shall be kept to a minimum. This will be accomplished by the following: a. The equipment will be made available to the crews at the prearranged time. b. The crews will be ready to start work at the prearranged time. c. The crews will release the equipment promptly upon completion of the work. d. Federal power and water system equipment will be returned to service as soon as possible. e. Events such as shift changes and lunch periods, and overtime considerations shall not unduly impede or delay returning equipment to normal. II. DEFINITIONS 2.1. Agency (capitalized) means Reclamation or Western, 4 or departure during normal work hours. Activities outside of normal work hours are to be reported as defined for un- attended stations. IV. MATERIALS FOR USE WITH THESE PROCEDURES AND INSTRUCTIONS 4.1. SWITCHING PROGRAM FORM. 4.1.1. PURPOSE. The Switching Program Form is used to formalize and document each step in the process of establishing and releasing Clearances, Hot Line Orders, Special Conditions, and performing General Switching. The needs of the Regions/Areas vary; therefore, one standard form may not be practicable at this time. How- ever, Region/Area and Area/Area interfaces are encour- aged to develop uniform Switching Program Forms wherever possible. A typical Switching Program Form is shown in figure 1. Figure 2 is a typical Switching Order (Reclamation only) which may be used to supplement the Switching Program Form to facilitate switching at locations remote from the Control Center. These forms are not available from Reclamation or Western stock. Each Region/Area interface shall, for its specific needs, develop Switching Program Forms which provide documentation for three main categories: ( 1) "request and action taken" information; (2) switching placement program; and (3) switching removal program. Space for other information may be provided. Entries on the Switching Program Form should be typewritten or printed using permanent marking material. 4.1.2. APPLICATION. A Switching Program Form or Switching Order, when applicable, shall be completed by the responsible Operations Supervisor and checked by a second qualified person, where possible, for all opera- tions requiring a Clearance, Hot Line Order, Special Condition, or General Switching. It is desirable that 11 copies of the appropriately filled-in form be sent in advance (either hard copy or by data transmittal equip- ment) to each location involved in the program for reference c;nd use by the Switchman during the switching and tagging operation. Upon receipt of an advance copy, the Switchman will contact the Control Center or Dispatch Office and read back the Switching Program to verify that he understands what actions are to be accomplished by the order. In lieu of an advance copy, the Operations Supervisor may provide the information by available com- munication channels to the Switchman or second Operations Supervisor, who will write all information on the Switching Program Form pertinent to his location and upon receiving all steps in the switching program, the switchman shall read back the entire switching program step-by-step. Switching Program Forms shall be reviewed by the Operations Supervisor and the Switch- man immediately prior to switching. The person receiving and reviewing the Switching Program Form should also perform the switching. The Switching Program Form used by the Operations Supervisor (Master Copy) shall clearly indicate which instructions are to be accomplished at each station. It is intended that all documentation for operations covered by this Document be done on the Switching Program Form to eliminate duplication of information on other forms, logs, or tags. Upon com- pletion of the work, the Switching Program Form shall be kept as a permanent supplement to the Operations Supervisor's log. However, to limit interruption time to customers, it is permissible for the Operations Supervisor to direct emergency sectionatizing switching, and log operational times, without documenting this information on a Switching Program Form. 4.1.3. NUMBERING. Each Switching Program Form for Clearances and Hot Line Orders shall be given a unique serial number. Each Switching Program Form for Special Conditions and General Switching should be given a 12 unique serial number. The necessary coding for the year and facility shall be prescribed by the Regions/Areas. One series of consecutive numbers may be used for all programs or a separate series of consecutive numbers ·may be used for Clearances, Hot Line Orders, Special Conditions, and General Switching. The form shall indicate whether the procedure is a Clearance, Hot Line Order, Special Conditions, or General Switching. 4.1.4. INFORMATION. "Switching for Placement" and "Switching for Removal" are the parts of the Switching Program Form used to record in detail the exact operation required and the tagging information. Each operation shall be listed in the precise sequence to be performed including those operations or steps not requiring a tag. There shall be only one operation per step on the Switching Program Form. The location of the Safety Tags and Hot Line Tags define the perimeter for Clearances and Hot Line Orders. 4.2. LOG ENTRIES. All entries shall be typewritten {manual or computer generated printout) or legibly hand- written in ink, or other permanent marking material. Entries shall be made as soon as practicable after the action has been accomplished. The name of the person making entries shall appear in the log. In addition to the documentation provided by the Switching Program Form, entries in the Dispatch Center, Control Center, and/or station log shall be made as follows: 4.2.1. PLACEMENT ACTION. After the placement operatiof1s are complete and the action has been issued, the Operations Supervisor shall log the "date ,""time ""type of action __ _ (Clearance, Hot Line Order, Special Condition, or General Switching)," "assigned No. ,"''issued to ___ ,"and "equipment covered by action " 13 _.... -J::>. lliii£AU Of" ~ECLAMAtiON UNITED STATES DEPARTMENT OF ENERGY WESTERN AREA POWER ADMINISTRATION UNITED STATES DEPARTMENT OF THE 1NTtRIOR--BUR£AU OF RECLAMATION SWITCHING PROGRA• FORM ~oR:TI-CQiiUiosc QGS St.\liOM(Sf (QUIMMl TAKEM-Ounjf SERY ICE AE\)1.1 IRED TIN( DATE WOI! I( TO It PEIU'-ORHfD REQUESTED BY 0 8£ ISSU£0 TO NOTifiCATION TO OTHERS I'J.D£ f"o. t'm'l"fF!i"l\'ll'rnmr--vno::mr.r'f':'::r;:hr;;;;:-;~;-;;::;;;--;-;;-;;;'Ou7.~-;:w:;;;;;:w.:*·----------------------- ··swr TCRIIIG FOR l'l:TCU4lliT SiiTCHIMG fOR REMfiUL pfltp AJI:[OIY C:HECK£0 II\' PREPARED BY I CHECKED BY O£TAIL£D SWITCHING AIIO EOUIPM£MT TAG NO I TIM£ I PEIIFORMEO BY TAG 110 OET.I.Il[D SWITCHING AND fOUIMMT ~-1 P£HFORI!frlBY ,._ --... -·~--··-------------J----r-----------------------------+--·---r--------- -----------------l---1---+·-----l-----"------"--· ----------·- -·-+-I --+--·!---·-- ---1-----· --------·t··-----· ·r--~r=---------- · -----··--+--+1 __ J ___ J ____ .... ~ ---~:r=-------------------· ------------------------------t-3 ___ 3 _____ « ·r ----. ···----.. -·-··-· -----··-· --·. ---------··-· .. ·--··--t----~-------·· ·-·~ -----------------__ ... ,•--___ w ________ _ t-- -·---------------------+--+--··· ··--·--~ .... ,.._. -~-. ------ ---·····-··-·- MO. I SSU£0 TO I SSU£0 6Y TIME OAT£ "0 . RELEASED BY Rft fJ.SfO TO TIMF OHE +-----· ... ---+--"' --------~-+---+----+----- Figure 1 (NOT USED BY WESTERN) U. S. DEPARTMENT OF THE INTERIOR BUREAU OF RECLAMA liON POWER PLANT SWITCHING ORDER S. 0. NO. __ CLEARANCE NO.------ISSUED TO -------- STATION-------------------- ORDER RECEIVED ___ M ________ 19 __ _ -------REC'D. 8Y -------- ORDER DETAIL ORDER EXECUTED BY: Figure 2 SWITCHING ORDER FORM 15 TIME i i I l I ' I I I 4.2.2. REMOVAL ACTION. After a Clearance, Hot Line Order, or Special Condition has been released and the removal operations and/or General Switching has been completed, the Operations Supervisor shall log the "date ," "time ," "type of action __ _ (Clearance, Hot Line Order, Special Condition, or General Switching)," "assigned No. ," "released by ,"and "equipment covered by action " 4.2.3. SWITCHING FOR LINE CLEARANCES. When switching for a transmission line Clearance, the Switchman shall log the "date , " "time ___ " "completed switching for placement (or removal) of Clearance No. ." The Switchman will also log clearance data required by paragraphs 4.2.1 or 4.2.2 as applicable. 4.2.4. It is imperative that each Region/ Area develop a systematic method of keeping appropriate personnel informed concerning the status of Clearances, Hot Line Orders, General Switching, and Special Conditions. To accomplish this, the following are minimally required: a. The placement action log entry will be made in a distinctive color of ink, or a rubber stamp will be used to stamp the required format data in the log as shown in paragraphs 4.2.1 and 4.2.2. A distinctive color of ink may also be used for placement and removal actions using this stamp. b. A readily accessible file will be maintained at the Dispatch Office or Control Center of Switching Program Forms for current Clearances, Hot Line Orders, Special Conditions, and if available, Special Work Permits. 16 c. The Operations Supervisor will record current Clearances, Hot Line Orders, (and Special Work Permits, if available) at the beginning of each workday. A list of current General Switching and Special Conditions will be maintained and reviewed daily. 4.2.5. Errors in log entries shall be voided by drawing a single line through the error and shall be initialed by . the person making the deletion. Under no circumstance will pages be removed from permanent logs, either manual or computer generated. 4.3. SAFETY TAGS. These tags are used in connection with Clearances and Hot Line Orders to convey the warning, DO NOT OPERATE, as discussed in sections V and VI. Only approved, prenumbered, red plastic-type Safety Tags shall be used. Unnumbered tags (figure 3) are stocked at Reclamation's Denver office (code D521 0) or Western's Headquarters office (code A 1540) and are available on request. Each Region/ Area shall designate and affix appropriate sequential identifying numbers and/or letters to at least one side of each tag. The choice of tag identifying numbers and/or letters must assure that there is no possibility of confusion with other tags used in the same or an adjacent operating area. 4.4. HOT LINE TAGS. These tags are used in connection with Hot Line Orders to prevent reenergizing equipment, as discussed in section VI. Only approved, prenumbered, yellow plastic-type Hot Line Tags shall be used for this purpose. Unnumbered tags (figure 4) are stocked at Reclamation's Denver office (code 0521 0) or Western's Headquarters office (code A 1540) and are available on request. The tags shall be uniquely prenumbered by each Region/Area. 17 4.5. SPECIAL CONDITION TAGS. These tags are used to designate special conditions affecting equipment as discussed in Section VII. Only approved tags (figure 5) shall be used for this purpose. These tags are stocked at Re9lamation's Denver office (code D521 0) or Western's Headquarters office (code A 1540) and are available on request. The tag is to be numbered and completed in ink or typewritten. 4.6. SUPERVISORY CONTROL TAGS. These tags are to be used on superVisory control points as discussed in Section IX. The tags shown (figure 6) are for illustrative purposes only and show the minimum amount of information required. There is a wide variety of supervisory equipment in use in Reclamation and Western; therefore, it is not practical to prepare a standard set of tags which will fit all supervisory control panels. Each Region/Area is respon- sible for developing tags for its own use, using the indicated color system. 4.7. DANGER TAGS. These tags are for the protection of the workman and shall be used by the workman as dis- cussed in section VIII. These tags (figure 7) are stocked at Reclamation's Denver office (code D521 0) or V.Jestern's Headquarters office (code A 1540) and are available on request The tag is to be completed in ink. 4.8. SPECIAL WORK PERMIT FORM. The Special Work Permit Form formalizes and documents the preparation and coordination between Agency and non-Agency personnel to authorize work by contractors and non-Agency construction or maintenance forces on or near Agency power or water facilities. The Special Work Permit Form (PO&M-169 or WAPA F6500.15) (figure 8) is available on request from Reclamation's Oenver office (code D521 0) or Western's Headquarters office (code A 1540). 18 T ::1 F .l ~ _ -~ -~ .:; ~ : _ : ·: ~ : ~-j G T 4 ::; T C'· .;. .' ~ . ., ' • :) ~ ,:; 7 -~ : S :/ I H / / ;' SAFETY TAG .·~ © DO NOT OPERATE MEN WORKING BACK Or U S DEPT OF Ei\jERG 't \N~STERN AREA POWER ADMINISTRA ;,ON SAFETY TAG DO NQl OPERATE • MEN WORKING -.0. FRONT POU 137 (1-61} Figure 3 SAFETY TAG 19 --z: TO BE PRE\JL\laE::::E_ By~"'<= =(,:g ::-.>c.; _ 3 -:-:-JF c\JERG'r .'.=::.-;:::::\ .:-:.: :'::.::::{ .;,Jivll~j!S:RAT:QN ~~~~~----------~------------~~/ . ~~ // I i~ ~ HOT LINE TAG N 0. I ~g BEFORE REENERGIZING l 0 WAIT UNTIL CONTACT PO 8 M · I 35 ( 1-6 7 l RED LETTERING -- BACK Figure 4 HOT LINE TAG 20 U.S. DEPT. OF ENERGY WESTERN AREA POWER AOMINISTRA TION Or U.S. DEPARTMENT OF INTERIOR BUREAU OF RECLAMATION HANDS OFF DO NOT OPERATE S1gned by ______ _ Dote ___________ _ PO 8 M-166 ( l-67l Figure 7 DANGER TAG 23 ,.-LARDBOARD "' 130DY This form provides: a. A documented protective action (Clearance or Hot Line Order if required) on a specified Agency power or water facility. b. A statement that the undersigned have discussed the work to be done, reviewed the details of the above documented protective action for adequacy, and defined the perimeter and.conditions of the safe working area. c. A written description and/or drawings identifying the perimeter of the safe working area. d. Space for the signatures of the Agency and con- tractor's representatives at the worksite indicating full agreement and understanding, together with the date and time that it is satisfactory to proceed with the work. e. A release statement to be signed by the contrac- tor's representative that the work has been completed. V. CLEARANCES 5.1. PURPOSE. Clearances are used to establish, under a controlled discipline, a safe environment within which Work- men can perform their assigned tasks. A CLEARANCE IS USED PRIMARILY FOR PROTECTION OF PERSONNEL BUT MAY INCIDENTALLY PROVIDE PROTECTION FOR EQUIPMENT. The clearance procedure is intended to accomplish this protection with as little delay and incon- venience as possible. 5.2. OBJECTIVE. Clearances are accomplished by systematically isolating the equipment from all sources of 25 AVTEC Power Plant synchronization 00 BUREAU OF RECLAMATION FACILITIES INSTRUCTIONS, STANDARDS, & TECHNIQUES Volume 4-8 HERBICIDES AVAILABLE FOR TREATING SOIL FOR VEGETATION CONTROL Material in this volume was provided by: John E. Boutwell, Environmental Sciences Section, ACER Alan L. Ardoin, Water and Power Operations Branch Howard E. Watson, O&M Engineering Branch, Editor August 1992 Herbicides Available for Treating Soil for Vegetation Control This volume contains an approach to control vegetation in Reclamation switchyards, substations, and maintenance areas. The Department of the Interior and the Bureau of Reclamation are recommending an integrated pest management approach to all vegetation control procedures. Although the herbicides listed may be a solution for controlling vegetation in Reclamation switchyards substations, and maintenance areas, it is recommended that more environmentally compatible measures be taken whenever and wherever possible. A least toxic approach should be considered when selecting a vegetation control method. This means selecting a biological control method over a mechanical or chemical control method if similar results can be obtained. Some alternative vegetation control methods to be considered around maintained facilities include grazing (of open areas), planting of low growing grass varieties, moving, cultivation, and the use of vegetation inhibiting materials such as geotextiles, gravel (road mix/road base-this mixture of gravel and fines does a better job of holding herbicides than uniform sized gravel), riprap, asphalt, and concrete. In the event that a herbicide is needed, an integrated approach should be considered, combining one or more of the above recommendations with a herbicide. Herbicide selection should follow the least toxic approach, i.e. selective, nonselective, nonselective persistent Some herbicides have been omitted from the listing because they are considered to be problem herbicides, i.e. ground water contaminants, toxic to wildlife, etc. Conversely some herbicides which are not considered to be true soil applied herbicides have been omitted, but may provide very good vegetation control and at the same time be less toxic than the herbicides listed. The sample trade names listed are not necessarily the only manufacturer of the listed chemical and any listing of the trade name does not constitute any endorsement of that product. It is recommended, that if a herbicide is selected over other means of vegetative control, the selected herbicide be verified appropriate for the intended use and/or area by local county agricultural agents, herbicide manufacturers, herbicide labeling information, or similar authority. NOTE: Some lateral movement of the herbicides listed may be experienced, and precaution should be taken to prevent erosion of treated soil. Strict adherence to application procedures and material safety obtained from the product label should be maintained. 1 Herbicides Available for Treating Soil for Vegetation Control Chemical Sample Trade Names General Uses and Precautions bromacil Bromax4G Non-selective herbicide for total weed and Hyvar X brush control in noncrop areas. Use under asphalt, concrete, and pond liners to extend useful life of the surfacing material. Avoid contact with skin, eyes, and clothing. Avoid inhalation of dust or spray. Do not allow spray drift to come in contact with desirable vegetation. Liquid formulation is combustible - keep away from heat and open flame. chlorsutfuron TelarDG Use as a non-selective weed control on broadleaf plants, annual and some perennial grasses, or reduced moving herbicide. Temporary irritant to eyes, nose, throat, and skin. Therefore avoid skin and eye contact. Avoid breathing dust or spray mist. ·-clopyralid Transline Non-cropland areas, industrial sites, and rights of way. For selective control of broadleaf weeds. Mix with Telar for thistle control. Avoid contact with skin and eyes or clothing. Avoid breathing spray mist. Wash thoroughly with soap and water after handling. diu ron Direx80W Apply around utility, pipeline, storage, and Kennex OF industrial areas. Total weed control of noncrop areas. Some registered for application to dry ditches during noncrop season. Avoid skin and eye contact. Avoid inhalation of dust or spray. Do not allow spray drift to come in contact with desirable vegetation. Do not contaminate domestic water supplies. 2 Herbicides Available for Treating Soil for Vegetation Control Chemical Sample Trade Names fosamine Krenite S (+sodium gluconate) glyphosate Roundup hexazinine Vel par imazapyr Arsenal General Uses and Precautions Add 4 ounces sodium gluconate per gallon Krenite S. Apply to noncrop areas, drainage ditches, dry marches, dry deltas, dry flood plains, and transitional areas between upland and lowland sites. Effective on numerous bottomland hardwoods and leafy spurge. Avoid contact with skin and eyes or clothing. Avoid breathing spray mist. Wash thoroughly with soap and water after handling. Not a residual herbicide -annual treatment is needed. For use around railroad, pipeline, and telephone rights of way, schools, parks, and golf courses. Avoid contact with skin and eyes or clothing. Avoid breathing spray mist. Wash thoroughly with soap and water after handling. Controls many annual and biennial weeds, woody vines and most perennial weeds and grasses (except Johnson grass) on noncrop areas. Apply during a period of maximum growth. Do not overspray onto desirable plants or the area where their roots may extend. As with all herbicides, avoid breathing spray or dust. Wear protective clothing. Irritation to the mucous membranes may occur. Apply as either preemergent or post emergent to control most annual and perennial grasses and broadleaf weeds on noncrop lands. Can be applied prior to paving or the placement of pond liners. Although translocation is rapid, plant kill can be slow. Avoid contact with skin and eyes or clothing. Avoid breathing spray mist. Wash thoroughly with soap and water after handling. 3 (\~- Herbicides Available for Treating Soil for Vegetation Control Chemical prometon Sample Trade Names General Uses and Precautions Pramitol 25E Use in area where complete control of vegetation is desired (around buildings and industrial areas). Do not use on cropland or near desirable trees, shrubs, or other desirable plants. Nonflammable, noncorrosive, stable shelf life. Avoid skin, eye, and clothing contact Wear eye and inhalation protection. sulfometuron methyl Oust Apply before or during early growth stages of weed growth as a preemergent or post emergent to control broadleaf weeds and grass. Apply to noncrop areas, such as railroad, highway, utility, and other rights of way. Selective weed control in certain types of unimproved turf grasses on noncropland. tebuthiuron Spike 20P May,irritate eyes, nose, throat, and skin. Avoid breathing dust or spray mist Avoid contact with skin, eyes, and clothing. Non crop control of right of way areas. Degree and duration of control will vary with amount of chemical applied, soli type, and other conditions. Apply either preemergent or post emergent. Avoid application and spray drift on to desirable trees or other plants as well as their root zone. Do not apply to irrigation or potable water. Avoid breathing dust and contact with skin, eyes, or clothing. Use eye protection and protective clothing such as coveralls and gloves. 4 1. INTRODUCTION 1.1 Purpose INSPECTION OF PENSTOCKS AND PRESSURE CONDUITS Many of the penstocks and pressure conduits at Bureau of Reclamation (Reclamation) facilities are over 40 years old. Corrosion and erosion have reduced the strength of these structures to values less than original design strength, and changes in capacity or operations have resulted in more severe service than was originally anticipated. The Federal Energy Regulatory Commission (FERC) has become increasingly concerned about the number of penstock failures or other potentially dangerous incidents that have occurred in the operation of penstocks. The FERC has recognized the potential for loss of life and damage to the environment and has mandated inspection and testing of penstocks for private utilities. The purpose of this document is to provide inspection and testing guidelines that meet or exceed the FERC mandate and to avoid the occurrence of a penstock failure. The main purpose for implementing a penstock inspection program is to ensure that each penstock is safely and efficiently operated and maintained. Some of the benefits that result from regularly scheduled penstock inspections are listed below: • Improvement of facility and safety of personnel and public • Prevention of damage to the environment • Improvement of reliability • Reduction of operation and maintenance costs • Minimization of unscheduled outages • Minimization of liability Much of the material presented in this document was obtained from several publications written by the American Society of Civil Engineers (ASCE) Hydropower Committee. These documents include: Steel Penstocks (ASCE, 1993), Guidelines for Evaluating Aging Penstocks (ASCE, 1995), and Guidelines for Inspection and Monitoring of In-Service Penstocks (ASCE, in preparation). 1.2 Inspection Procedures The procedures for inspection of a penstock or pressure conduit are listed below in sequential order: 1. Perform an initial assessment, which includes a thorough visual examination of the following items: penstock shell condition (interior and exterior), welds, bolts and rivets, expansion joints and sleeve-type couplings, air valves and vents, control valves, manholes and other penetrations, anchor blocks and supports, appurtenances, linings and coatings, and instrumentation. 2. Record penstock shell thickness measurements using non-destructive examination (NDE) methods (usually ultrasonic) at selected locations along the penstock. This task could be combined with the initial assessment described above. 3. Perform a detailed assessment using NDE techniques for specific items of concern that were observed during the visual examination. 4. Simulate the emergency control system operation to ensure the emergency gates ·or valves will close and that documentation (physical test or calculations) exists to indicate they will completely close. 5. Perform load rejection tests for comparison against hydraulic transient analysis results and design criteria to ensure safe operating conditions. 6. Readjust the governor to establish a safe wicket gate timing to prevent over- pressurization of the penstock and to ensure maximum response capability. 7. Have design personnel evaluate the data obtained during the penstock inspection. This evaluation should typically include tasks associated with data and stress analysis and a determination if the penstock is in accordance with defined acceptance criteria. 1.3 Frequency of Inspections The inspection frequency may vary from 1 to 5 years, but should not exceed 5 years. Factors to be considered in recommending the next inspection date include: Accessibility for inspection • Overall condition of the penstock or pressure conduit Type of design and the age of the penstock or conduit Existence of significant public safety concerns • Existence of significant environmental concerns The need to document the condition of the penstock or pressure conduit • Criticality of the facility to power production and water operations Once these and other pertinent factors have been addressed, the inspection frequency can be established. Minimal guidelines for inspection frequency are as follows: 2 • Monthly inspection: A visual observation of exposed penstocks should be performed through a monthly walkdown by operations personnel. If this observation is not practical because of excessive length, rough terrain, etc., then the walkdown should be performed at least once a year. The interior and exterior surfaces of penstocks and pressure conduits should be visually examined every 2 to 3 years to note the condition of the linings and coatings. A thorough penstock inspection, which includes the procedures described in section 1.2,should be. performed every 5 years. 1.4 Inspection Records To establish an accurate repr~sentation of the penstock condition at a given hydroelectric facility, the in-service inspection program must be well documented and implemented by facility personnel. A log should be established at the plant to record the date, type of inspection performed, and results of all inspections performed on penstocks. Inspection results should be forwarded to the engineering staff or other appropriate personnel for review and evaluation. These records must be maintained for future reference. A documented chronology of inspections, results, evaluations, and repairs will help identify the development of any adverse trends and is essential for the proper maintenance of safe penstocks. An inspection report should be prepared by one or more members of the inspection team. The report shall document the following items: • Dates of inspection • Inspection participants • Names of facilities inspected • Description of inspection activities • All technical investigations, data analyses, and design studies • All recommendations made during or as a result of the inspection Inspection reports should be distributed to all inspection participants and groups associated with the facility. The reports should be kept on file by the responsible office for a minimum of 10 years. 3 2. PRE-INSPECTION WORK 2.1 Inspection Plan The inspection plan is a key element of a successful penstock assessment. should include the following items: 1. Scope and goal of the inspection 2. List of personnel involved or required 3. A checklist of the items to be inspected 4. Dates and times of the inspection 5. List of clearance points and equipment to be locked out/tagged out to ensure a safe penstock inspection. 2.2 Scheduling Penstock inspections need to be planned and scheduled to minimize down time of the turbine units. If possible, the penstock inspection should be performed during a scheduled unit outage. 2.3 Safety Plan A safety and hazard analysis should be prepared for the penstock inspection. Make certain that all personnel working at the site receive a copy of the safety hazard analysis and acknowledge that they have read the contents, understand the safety requirements for the tasks they are performing, and will implement the safety requirements at all times during the field work. Some items which should be a part of the safety hazard analysis for a penstock inspection are listed below: 1. List the contacts for reporting accidents. 2. List emergency telephone numbers. 3. List addresses and directions for local hospitals. 4. Highlight the facility's safety manual that pertains to site investigation activities. 5. Field review the site working conditions and possible safety hazards. A safety checklist containing some, but not all, important safety items appears below: • All equipment and facilities should have safety tags placed on the controls, doors, and entrances by authorized personnel. These tags cannot be removed 4 -STOP GATES Waterman Stop Gates can be fitted with either rod handles· or a slot grip for hand placing. Guide rails for embedded, flatback or channel mounting are available. These gates are designed for a maximum head of one foot over the slide, unless otherwise specified and are used generally in diversion applications. Options available include "J" Bulb seals for minimum leakage, ultra high molecular weight polyethylene seats for increased ease of operation and special cut outs such as "V" notch or slot openings for water measure- ment. All frames feature welded construction. Slides are minimum %"thick to minimize deflection and contribute to long gate life . Available in an almost unlimited range of sizes and configurations, Waterman stop gates can be manufac- tured from aluminum, steel , stainless steel or fiber- glass. Aluminum Stop Gate RADIAL GATES USES: • Maintenance of water elevations in canals or spillways •Increased storage capacity for reservoirs • Diversion of water for irrigation • Flow control preserving wide, clear waterways • Other areas requiring economical water control Waterman Overflow or Breastwall-type Radial (Tainter) Gates can be engineered for unique applications or can be manufactured from a standardized Waterman de- sign. In either case, they are always made to the customer's exact specifications. They provide a light- weight economical gate that can be opened and closed with a minimum of effort. Waterman Radial Gates can also be ordered for existing locations as replacement gates. CONSTRUCTION FEATURES THE FACE PLATE The face plate is accurately curved on a required radius to an engineered pivot point. This plate is buttressed along the backside with vertical ribs radiused to match the face plate and stiffened with horizontal support beams along the total width of the plate. The horizontal support beams vary in size with the width of the gate and the maximum head of water. They transfer the pres- sure from the face plate to the radial arms. SEALS Waterman provides two types of seals. For overflow and breastwall-type gates, J-bulb seals are securely attached along both sides of the face plate. This provides a positive seal against the adjustable rubbing plates embedded in the side wall, and on the bottom of the face plate to seal against the invert. For breastwall- type gates with which there is a headwall, an additional flat seal is attached at the top ofthe faceplate for sealing against the headwall. Waterman makes available flat, wiper-type rubber seals In place of the J-bulb type. This type of seal is especially useful for existing installations in which there are no side rub plates. RADIAL GATES BOTTOM AND SIDE SEALING PLATES If desired, Waterman can supply galvanized or stain- less steel rubbing plates to provide a smooth contact surface for the side seals throughout the full range of movement of the gate. These plates adjust to permit vertical alignment of the contact surfaces. Galvanized or stainless steel bottom sill plates can be supplied to provide a smooth level contact surface for the full width of the invert of the gate. This sill plate can be adjusted to permit leveling and alignment with the side plates. RADIAL ARMS Acting like columns under an arch, radial arms transfer the pressure from the face plate assembly to the pivot bearings on either side of the gate opening. Fabricated from structural steel shapes, larger and thicker mem- bers are used as the gate height increases. The radial arms are accurately punched on the forward or up- stream end to match corresponding holes in the hori- zontal support beams. On the downstream end, a steel pin plate assembly is securely welded to the arm to transmit the force to the pivot pin. PINS AND PIN BEARINGS Type 304 stainless steel pivot pins transfer the load to bronze bearings encased in cast iron housings, which are firmly anchored in the concrete structure. The bearings are permanently lubricated or grease lubri- cated and have sufficient surface area to properly distribute the full load to the structure. HOISTS All Waterman Radial Gates are actuated by cabledrum hoists, each system having twin drums connected by a shaft for winding the two operating cables simulta- neously. For powering the cabled rum, Waterman makes available three variations of actuators -a manual hoist with exposed gears; a manual hoist with enclosed gears; and an electric motor operated hoist with auxil- iary handwheel. BOTTOM SEAL DETAIL AESJLIENT SEAL NEOPRENE STRIP SEAL PIN BEARING DETAIL SIDE SEAL DETAIL TOP SEAL DETAIL (BREASTWALL TYPE) 75 AA-6 PRESSURE RELIEF VALVE • PROTECTS PIPE LINE FROM SURGES • AVAILABLE IN 2" AND 21h" SIZES USES: This moderately priced valve is especially suitable for most aluminum sprinkler and higher pressure plastic pipe. FEATURES: Dependable, time-proven design with the spring on top, out of the flow, for longer, more accurate operation. Constructed from high strength aluminum castings with stainless steel shaft, tempered steel spring, and non-sticking Teflon seal and bushing. This valve may be ordered factory set and sealed under actual hydrostatic conditions, or can be shipped to you for final field adjustment. When ordering field adjustable units, be sure to specify pressure range as Waterman uses springs with different compressive strengths to maximize the amount of release when excessive pressures occur. Sizes: 2" and 21h" Pressure relief settings. 11 to 120 p.s.i. Specify AA-6A if preset Specify AA-68 if fieldset PARTSUST No. Name Qly. 1 Base 1 2 Cover 1 3 Guide Rod 1 4 Nut 2 5 Seal Wire 1 6 Spring Ratainer 1 7 Sprilg 1 8 Washer 1 9 0-RirG 1 10 Cover GaskeUSeal Face 1 11 Gasket Relainer 1 w/ScreNs 12 Bushirg 1 2" & 21h" Model AA-6 Factory set and sealed or shipped for field setting wfter:mon .. ~ -c :::0 m en en c :::0 m :::0 m r -m "TT < )> r < m en 22C C-20 CANAL GATE • 10 foot Unseating Head • Up to 35 foot Seating Head (see chart) • Rugged Cast Bronze Lift Nut • Machined Iron Seats, standard • Rising Stems • Adjustable Side Wedges USES: The Waterman Model C-20 Canal Gate is made to fit the need for a moderate pressure cut-offwhere either moderate seating or low unseating pressures are encountered . Typical uses indude installation in treatment plants, flood control projects, irrigation canals and diversion stands. FEATURES: Flatback gates for headwall mounting or spigot back models for attaching to corrugated met~l pipe are available . The cover, frame ring, adjustable wedges, arch, and handwheel are made of cast iron . The lift nut is cast bronze and utilizes rugged acme type threads. The steel stem is secured to the cover by an easily remov- able pin to permit removing for maintenance. This feature also allows the user to stock standard frame length gates and provide field installation of rising stem extensions, where this is desirable . Standard accessories, galvanizing, and bronze seats and stems are available. Flatbackflanges with 25#or 125#ANSI standard drilling available on special order. A variety of sizes are available and custom require- ments may be furnished. • Stainless Steel Guide Rails and Stem, optional • Bronze Seats, optional • 25# and 125# ANSI drilling, optional RECOMMENDED MAXIMUM SEATING and UNSEATING HEADS RECOMMENDED RECOMMENDED GATESEZE MAXIMUM MAXIMUM SEATING HEAD UNSEATING HEAD 8" 10 12" 35 FEET 10 FEET 14" TO 18" 32FEET 10 FEET 20" T024" 26 FEET 10 FEET 30" 1042" 20 FEET 10 FEET • These recommendations are based upon design studies and modifications of this valve and upon years of installation evaluations. ~ IIOJSt'REI, ~ ·~ FACILITIES INSTRUCTIONS, STANDARDS, AND TECHNIQUES VOLUME 2-3 MECHANICAL GOVERNORS FOR HYDROELECTRIC UNITS Revised 1990 William Duncan Jr. Revised 2002 Roger Cline HYDROELECTRIC RESEARCH AND TECHNICAL SERVICES GROUP UNITED STATES DEPARTMENT OF THE INTERIOR BUREAU OF RECLAMATION DENVER, COLORADO CONTENTS Section Page 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2. Governor Fundamentals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.1 Speed Sensing Governor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.2 Speed Droop Governor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.3 Compensating Dashpot. ....................................... 3 3. Generaf Description of Mechanical Governors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. 1 Ball Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2 Hydraulic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.3 Speed Adjustment ........................................... 4 3.4 Gate Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.5 Auxiliary Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.6 Shutdown Solenoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. 7 Transfer Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. Servomotor, Wicket Gate, and Governor Hand Alignment . . . . . . . . . . . . . . . . . . . 6 4.1 Servomotor Alignment or Squeeze Adjustment . . . . . . . . . . . . . . . . . . . . . 6 4.2 Wicket Gate Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.3 Gate Position/Gate Limit Head Alignment of Woodward Mechanical Actuator ................................................. 8 4.4 Gate Position and Gate Limit Head Alignment of Pelton Mechanical Actuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5. Remagnetizing the Rotor of a Woodward Permanent Magnet Generator ....... 14 6. Testing and Adjustment of Mechanical Governors ........................ 16 6.1 Wicket Gate Timing ......................................... 16 6.2 Optimizing Governor Performance .............................. 16 7. Governor Adjustment Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 7.1 Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 7.2 Wicket Gate Timing ......................................... 19 7.3 Setting up the PMG Simulator (if Used) .......................... 21 7.4 Check and Adjust Permanent Droop . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 7.5 Adjust Speed Changer ....................................... 24 7.6 Adjust Dashpot . . . . . . . . . . . . . . . . . . . . ........................ 25 7.7 Check and Adjust Dither ...................................... 28 7.8 Normal Operations Check ..................................... 29 8. Governor Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 8.1 Governor Tests and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 8.2 Governor Ball Head (Woodward Vibrator Type) .................... 30 111 Section CONTENTS (Continued) Page 8.3 Governor Ball Head (Woodward Strap Suspended Type) . . . . . . . . . . . 30 8.4 Governor Ball Head (Pelton) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 8.5 Woodward Oil Motor Vibrator .................................. 31 8.6 Pilot Valve ................................................. 31 8.7 Main and Auxiliary Distributing Valves . . . . . . . . . . . . . . . . . . . . ..... 31 8.8 Miscellaneous Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... 31 8.9 Dashpot . . . . . . . . ......................................... 32 8.1 0 Links and Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 8.11 Restoring Cable · . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 32 8.12 Hydraulic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........... 33 8.13 Generator Air Brake Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3'3 8.14 Pennanent Magnet Generator (PMG) or Speed Signal Generator (SSG) . . . . . . . . . ............................... 34 8.15 Position and Limit Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 8.16 Shutdown Solenoids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 8.17 Speed Changer, Gate Limit Motors, and Remote Position Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 9. Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 9.1 Hunting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 9.2 Inability to Reach Full Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 9.3 Inability to Reach Full Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 9.4 Wicket Gates Sticking Midrange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Figures Figure Page 1 Speed sensing governor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 Speed droop governor . . . . . . . . . .................................. 1 3 Speed droop governor-speed vs. gate position . . . . . . . . . . . . . . . . . . . . . . . . 2 4 Speed droop governor-large power system . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 5 Speed droop governor with compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 6 Speed droop governor with compensation and speed changer . . . . . . . . . . . . . 5 7 Over and under travel of gate position indicator . . . . . . . . . . . . . . . . . . . . . . . . 9 8 Over and under travel with respect to gate limit . . . . . . . . . . . . . . . . . . . . . . . . 10 9 Schematic for remagnetizing PMG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1 0 Schematic for demagnetizing PMG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 11 Governor response curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 12 Wicket gate timing: closing ....................................... 20 13 Governor response with dashpot disabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 14 Simulated governor response curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 lY CONTENTS (Continued) Photographs Photo Page 1 Leveling compensating crank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2 Leveling studs on gate limit links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3 Restoring shaft bellcrank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4 Gate limit links . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5 Gate limit stop rod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 6 Auxiliary valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7 Pin C-48135 on gate position gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8 Slotted gate rocks haft lever ................................ ·. . . . . . . 12 9 Adjustment of relay valve restoring mechanism . . . . . . . . . . . . . . . . . . . . . . . . 13 10 Connecting rod H-42524-A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 11 Location of floating lever and pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 12 Auxiliary valve connecting rod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 13 Stopnuts on a woodward governor ................................. 21 14 Stopnuts on a Pelton governor .................................... 21 15 Woodward speed droop calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 16 Pelton speed droop calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 17 Woodward ball head and floating lever connecting rod .................. 24 18 Pelton speed adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 _,.... 19 Woodward restoring ratio adjustment ....... ~ ..... ~ ~ .......... ~ . . . . . 26 20 Pelton restoring ratio adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 21 Woodward dashpot and compensating crank ......................... 27 22 Pelton dashpot and compensating crank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 v MECHANICAL GOVERNORS FOR HYDROELECTRIC UNITS 1. INTRODUCTION The primary pmpose of a governor for a hydroelectric unit is to control the speed and loading of the unit. It accomplishes this by controlling the flow of water through the turbine. To understand how a hydroelectric governor operates, a basic understanding of governor fundamentals is helpful. 2. GOVERNOR FUNDAMENTALS 2.1. Speed Sensing Governor Speed control is one of the primary functions of a governor. A speed sensing governor in its simplest form is shown in figure 1. A set of rotating fly balls, opposed by a spring, controls the position of a valve. The valve controls the flow of oil to a servomotor that controls the throttle or, in the case of a hydro unit, the wicket gates. Any change in speed will cause the valve to be moved off its centered position, making the gates open or close, and changing the unit's speed. 2.2. Speed Droop Governor The speed sensing governor is inherently unstable and is not suitable for speed regulation. The undamped movement of the valve will allow the servomotor to move too far before the speed actually changes and the flyballs can react. This lag between the servomotor movement and the flyball response will lead to a severe "hunting" condition where the servomotor will continue to oscillate back and forth. Since there is no feedback of servomotor position, the valve doesn't know when to stop moving. To provide stability in the governor, feedback in the form of speed droop can be introduced. Figure 2 shows a simple speed droop governor. In the speed droop Speed Sensing Governor Speed Droop Governor I Close l .... --..-------.. I Close Pressure-----+ Drain Drain Figure I.-Speed sensing gfWernor. Figure 2.--Speed droop governor. governor, a decrease in speed will cause the valve to move upward, allowing the servomotor to drain and move in the opening direction. As the servomotor moves open, the valve is moved down by the speed droop lever, centering it over the port and stopping the servomotor. The unit is now operating at a slightly slower speed, but the servomotor will not overshoot because for a given speed the servomotor must move to a specific position. Speed droop by definition is the governor characteristic that requires a decrease in speed to produce an increase in gate opening. The graph in figure 3 shows the relationship between speed and gate position of a speed droop governor. A governor with speed droop set at 5 percent will require a decrease in speed of 5 percent in order to achieve full gate. A decrease in speed of 2.5 percent will cause the gates to open to 50 percent The speed droop is equal to the percent change in speed divided by the change in gate position. When the generator is part of a large system, no single unit is capable of changing the system frequency, and therefore, the unit must operate at the system frequency. This large system is referred to as an infinite bus. 1bis is how most plants are operated. When a unit is connected to an infinite bus, the speed droop controls the loading of the unit through adjustments of the speed changer. With a unit connected to an infinite bus, an increase in speed changer setting has the same effect as a decrease in speed of a unit operating off-line. Figure 4 shows speed changer versus gate position of a speed droop governor connected to an large power system. The speed is fixed at 100 percent. In this example, the governor is adjusted so that the unit is at speed-no-load with a 0 speed changer setting. With a speed changer setting of 2.5 percent, the load will be 50 percent. A 5 percent speed changer setting would result in 100 percent load. fi} UJ a. "' f-z Ul ~ w a. 00 >C 90 B5 80 75 65 60 55 Speed Droop Governor 5 PERCENT DROOP ·-1---- 50'--.. ---· 0 25 50 PERCENT LOAD 75 Figure 3.-Speed droop governor- speed vs. gate position. 100 2 Speed Droop Governor 5 PERCENT DROOP Connected to a large power system 05~·~-----------------------~ ~100~==------------~=== ~ 95 \ ti 90-.' U! Speed Changer Set a: 85 • al 2.5% Fast ~ 80 ~ 75 1:5 70 ~ 65 Gate Pos~ion w 6<![ at50% ~ ~t~----~------'~'----~----~ 0 25 50 75 Percent Gate Position Figure 4.-Speed droop governor- large power system. 100 2.3. Compensating Dashpot Speed droop alone usually does not provide adequate stability for an isolated power system or for a unit operating off-line. Figure 5 shows a speed droop governor with the addition of a compensating dashpot. The large plunger of the dash pot is connected to the servomotor so that its movement is proportional to the servomotor movement. Movement of the large plunger is hydraulically transmitted to the small plunger so that it moves a proportional amount in the opposite direction. The small plunger moves the valve to slow the response of the servomotor. A spring on the small plunger attempts to hold the plunger in its centered position. When the small plunger is moved off center, the spring will eventually recenter it. The rate at which the plunger moves to center is controlled by the setting of the needle valve. The needle valve provides an adjustable leak in the hydraulic system between the two plungers. Pressure Speed Droop Governor with Compensation Needle l Close --------____ .J The dashpot adds temporary droop to the Drain governor system and provides compensation for the effects of inertia of the unit and the water Figure 5.---Speed droop governor with compensation. column. Through the adjustment of the dashpot needle and the compensating crank, the governor response can be set to match the inertia and water flow characteristics of a specific unit. The needle adjustment allows the time required for the small plunger to recenter to be adjusted to match the time required for the unit speed to return to normal. The dashpot can provide stability in cases where servomotor movement is not great enough to provide sufficient feedback through the normal speed droop mechanism, such as operating off line at speed-no-load. When a unit is connected to a large power system, speed stability is usually not a concern and the damping from a dashpot is no longer required. The damping from the dashpot will cause a slower response to changes in speed changer adjustment. To provide a quicker response and allow the unit loading to be changed rapidly, most dashpots are equipped with a dashpot bypass. The bypass may be solenoid operated or operated through mechanical linkage and provides an addition leakage path to allow the small dashpot to recenter rapidly. The bypass is used only when the unit is operating on line and connected to a large power system If the unit becomes part of a small island, the bypass should not be used. 3. GENERAL DESCRIPTION OF MECHANICAL GOVERNORS There are numerous designs and configurations of mechanical governors, but generally, they have many of the same components. The main parts are a speed sensing device, usually a ball head, an oil pressure system, hydraulic valves to control oil flow, and one or more hydraulic servomotors to move the wicket gates. 3 3.1. Ball Head The ball head is the component that responds to speed changes of the unit. There are various designs of ball heads, but generally, they consist of two flyweights attached to arms that pivot near the axis of rotation. The arms are attached to a collar on a shaft. As the ball head rotational speed increases; the flyballs move out because of centrifugal force pushing a rod down. The rod, usually termed the speeder rod, acts on the pilot valve to route oil to the main valve and the servomotors. On a Pelton governor, the flyweights are attached to two leaf springs that are attached to the ball head motor at one end and the pilot valve plunger at the other. As the weights move out, the plunger is pulled down. The ball head is usually turned by a three-phase motor that is powered by a permanent magnet generator (PM G) that is driven by the unit being governed. The speed of the ball head motor is always directly proportional to the speed of the PMG and the unit. 3.2. Hydraulic System The hydraulic system consists of an oil sump, one or two oil pumps, an air over oil accumulator tank, and piping to the servomotors. Typically, there are two pumps with lead and lag controls so that there is always a backup pump. Some systems will share two pumps between two units so that in an emergency one pump could be used for both units. The accumulator tank is usually sized so that in the event the pumps fail, the gates can still be closed. The size of the valve required to control the large amount of oil flowing to the servomotors is too large to be controlled by the ball head. Therefore, a hydraulic amplifier system is used. Oil is routed to a servo on the larger valve by a small pilot valve. The pilot valve is very small so that it is sensitive to the small forces that result from small changes in speed. The larger valve may be called the main valve, regulating valve, control valve, relay valve, or distributing valve. The pilot valve usually is designed with a moveable bushing. The plunger of the pilot valve is connected, through a floating lever, to the ball head, and the bushing is connected to main valve. Whenever the pilot valve moves off center, oil is routed to the main valve servo, causing the main valve to move. The pilot valve bushing is moved off center by the main valve movement, blocking the port of the pilot valve, stopping further main valve movement. The restoring lever between the main valve and the pilot valve bushing is usually adjustable so that the ratio of pilot valve movement to main valve movement is adjustable. 3.3. Speed Adjustment The speed adjustment allows adjustment of the speed of the unit when it is offline, and it also allows adjustment of the loading when the unit is on line. The mechanism by which it accomplishes its purpose depends on the design of the governor, bufin all cases, adjusting the speed changer moves the pilot valve off center, which causes the gates to move (figure 6). If the unit is off line the gates will continue to move until the change in unit speed causes the fly balls to move enough to recenter the pilot valve. When the unit is on line and the fly balls are essentially in a fixed position, the gates will continue to move until the feed back from gate position through the speed droop mechanism recenters the pilot valve. The speed changer is usually calibrated from 85 to 105 percent of synchronous speed. 4 3.4. Gate Limit The gate limit physically limits the travel of the servomotors and wicket gates to the position indicated by the gate limit indicator hand. On Woodward governors, lowering the gate limit setting below the current gate position lowers a stop that acts on the top of the pilot valve plunger, forcing it down to route oil to close the gates. As the gates close, the restoring mechanism raises the stop so that when the gate position matches the gate limit setting the pilot valve is recentered, halting further motion. Speed Changer Speed Droop Governor with Compensation and Speed Changer Needle • tCiose Figure 6.-Speed droop governor with compensaJion and speed changer. On Pelton governors, the gate limit is provided by a separate gate limit valve. When the gate limit setting is above the gate position, the gate limit valve allows unobstructed flow between the pilot valve and the main valve. When the gate position matches the gate limit setting, the gate limit valves blocks all oil flow from the pilot valve. If the gate limit is moved below the gate position, the gate limit valve over-rides the pilot valve and routes oil to close the gates. With any governor, raising the gate limit setting -will not have any effect on the gate position unless the speed of the unit is below the speed setting when the unit is offline or the gate position is below the position called for by the speed changer setting when the unit is on line. In some cases, it may be desirable to set the gate limit at the desired load and increase the speed changer setting above what would be required to achieve that setting. When this is done, the pilot valve is trying to call for an increase in gate opening but is blocked by the gate limit. This is called a blocked load. 3.5. Auxiliary Control Most cabinet actuator type governors also have a smaller auxiliary valve to control the gate position. Because of the relatively small ports of the auxiliary valve, the gates are moved slowly and can be positioned precisely. The auxiliary valve has no connection to the ball head, and therefore, no speed control. There is also no protection from the shutdown solenoids when on auxiliary control. A unit should never be left unattended when operating -with the auxiliary valve. When operating with the auxiliary valve, the gates are moved by moving the gate limit The gate position will follow the gate limit where ever it is set There isn't an auxiliary valve on gate shaft governors, but in some cases, there may be a hand wheel that can be used to close the gates in the event the governor fails. 5 3.6. Shutdown Solenoid All governors have some sort of safety shutdown mechanism to operate automatically or manually to close the wicket gates in case of emergency. The device is usually controlled by a solenoid. In most cases, a weighted arm that is connected to the gate limit mechanism is held in place by the solenoid. If the trip is initiated, either automatically or manually, the solenoid is de- energized, dropping the weight, causing the gate limit to go to zero. A few installations have shutdo·wn solenoids that are designed so that they must be energized to trip. Typically, there is a manual emergency shutdown switch in the control room and at the governor cabinet. The solenoid is usually tripped automatically under any of the following conditions: generator or transformer differential relay operation, hot generator windings, overspeed, overcurrent, reverse current, ground fault current, low generator voltage, low governor oil pressure, or high bearing temperature. Depending on the plant, other conditions may also trip the shutdown solenoid. When the emergency shutdown solenoid is tripped, it must be reset manually. Many units also have a second solenoid operated shutdown device that is usually identical to the emergency shutdown solenoid. It may be used as a normal shutdown solenoid or a speed no load solenoid. If it is used as a normal shutdown device, its operation will still close the wicket gates, but unlike the emergency shutdown solenoid, it does not need to be reset manually. A speed no load solenoid typically moves the gate limit to some value just above the speed no load gate position. The speed no load solenoid is usually tripped during startup and shutdown while the breaker is open. This prevents unit overspeed if governor control is lost. 3.7. Transfer Valve The transfer valve is a three-way hydraulic valve that (1) permits the selection of the main distributing valve or the auxiliary valve for operating the wicket gates or (2) closes both valves. The main valve and the auxiliary valve each have plungers that can close off the pressure, opening, and closing ports of the valves. The bottom of the plungers have a smaller diameter than the top so that if oil is routed to the top of the plungers they will be forced closed. The transfer valve routes oil to the top of the plungers of the valve to be closed, forcing the three plungers in the valve ports down, sealing the valve shut. The top of the valve that is open is routed to drain, allowing the valve plungers to open. The block position routes oil to both the main and auxiliary valves closing both valves. Note: The block position is not adequate protection for working on or around the wicket gates or wicket gate linkage. 4. SERVOMOTOR, WICKET GATE, AND GOVERNOR HAND ALIGNMENT 4.1. Servomotor Alignment or Squeeze Adjustment During full closure of the wicket gates, the servomotor will continue to move a small distance past the zero gate position. This movement is referred to as the "squeeze" on the wicket gates. The squeeze acts to take up any slack in the wicket gate mechanism and applies force to hold the wicket gates closed against water pressure. 6 8. GOVERNOR MAINTENANCE 8.1. Governor Tests and Adjustments Annual adjustments: Check wicket gate timing and speed droop calibration as described in Section 7. Check the mechanical alignment of the governor as described in Section 4. If the dash pot, pilot valve, or any of the governor linkage is disassembled, adjust dash pot and compensating crank as described in Section 7. Five-year adjustments: Perform all the tests outlined in Section 7. 8.2". Governor Ball Head (Woodward Vibrator Type) Weekly adjustments: Oil the ball head by applying a few drops of light machine oil to the top of the ball head motor shaft. Check to see if motion can be felt with a finger between the main valve and base. If no motion can be felt, replace the vibrator and balls. Annual adjustments: After shutdown, remove the ball head and disassemble. Clean and inspect the slide blocks, fly ball rod, and fly ball rod bushings. Replace vibrators and vibrator balls if no motion of the main valve was felt before shutdown or if there is any noticeable wear on the vibrators. If sliding surfaces of slide blocks are worn, rotate both blocks to a new surface. Scribe an "X" or other mark on the worn slide block surfaces so they are not reused. Check flyball rod for wear and for straightness and replace as required. Check ball bearings in ball head motor and fly ball arms and replace as required. Replace flyball rod bushings if they are worn or scored. Cover vibrator balls with a light grease and reassemble. Do not fill vibrator cup with grease because this can dampen the vibration. Check operation of pressure type oilers if so equipped. 8.3. Governor Ball Head (Woodward Strap Suspended Type) Quarterly adjustments: Add dash pot oil to the top of the ball head motor to fill the internal dashpot. Do not use lubricating oil. Annual adjustments: Observe the operation of the ball head and check for any unusual vibration. If any abnormal vibration is noted, disassemble the ball head and the check condition of the thrust bearing, ball head shaft bearings, and ball head motor bearings. Follow the manufacturer's alignment and reassembly procedure. 8A. Governor Ball Head (Pelton) Apnual adjustments: Observe the ball head and the ball head motor for any unusual vibration or noise. Replace the ball head motor bearings if any abnormal vibration or noise is noted. Follow the manufacturer's instructions for disassembly and reassembly. 30 8.5. Woodward Oil Motor Vibrator Annual adjustments: Check that the oil motor vibrator is providing a 0.006 to 0.007 inch oscillation of the main valve and that the motor is turning in the range of 400 to 600 RPM (7 to 10 Hertz). Adjust the eccentric bushing in the pivot lever to change the magnitude of oscillation. Adjust the oil flow regulator to change the motor speed. 8.6. Pilot Valve Annual adjustments: Disassemble the pilot valve and remove all rust spots and oil varnish with a fine grade emery cloth (320 to 500) and crocus cloth. AnY nicks or scratches should be removed by stoning with a very fine flat stone. Care must be taken not to round or break the edges of the valve lands. If wear is excessive or the plunger does not move freely in the bushing, replace with a new matched plunger-bushing set. 8.7. Main and Auxiliary Distributing Valves Annual adjustments: Check that the main valve plunger is free. Shut off the oil supply to the pilot and main valves and disconnect the pressure supply to the pilot valve. With the oil pressure relieved, lift the main valve plunger until it hits the opening stop nuts and then drop it so it hits closing stop nuts. If the plunger drops freely, it is acceptable, but if there is any binding or if the plunger drops sluggishly, disassemble the valve to determine the problem Check the operation of the transfer valve and the auxiliary valve. Biannual adjustments: Remove the main and auxiliary valve plunger and remove all rust spots and oil varnish with a fine grade emery cloth (320 to 500) and crocus cloth. Any nicks or scratches should be removed by stoning with a very fine flat stone. Care must be taken not to round or break the edges of the valve lands. Check the ports in the valve bushings for dirt or sludge and clean as required. Check that the main valve plunger is free and can fall of its own weight after reassembly. Unscheduled adjustments: Completely disassemble the main and auxiliary valves. Remove opening, closing, and pressure plungers and remove all rust spots and oil varnish with a fine grade emery cloth (320 to 500) and crocus cloth. Check the condition of the main distributing valve plunger's piston rings, and replace as required. 8.8. Miscellaneous Valves Biannual adjustments: There may be other hydraulic valves in the governor such as gate limit valves and solenoid valves. These valves should be disassembled, and all rust spots and oil varnish should be removed with a fine grade emery cloth (320 to 500) and crocus cloth. Any nicks or scratches should be removed by stoning with a very fine flat stone. Care must be taken not to round or break the edges of the valve lands. Check the ports in the valve bushings for dirt or sludge, and clean as required. 31 8.9. Dashpot Annual adjustments· Check the dashpot oil level and add oil if necessary. Do not use lubricating oil. Check the operation of the solenoid operated bypass. If tests of section 7 indicate a problem with the dashpot, disassemble and clean the plungers. Before reassembly, check the setting of the small dashpot plunger. On Woodward governors, the distance from the center of the pivot pin to the top of the bonnet should be 2-7/8 inches. Turn the small plunger spring to adjust this distance. On other governors, check the manufacturer's instruction book for the adjustment procedures. To refill the dashpot, reassemble, except for the small dashpot plunger. Tip the dashpot so that the opening for the small plunger is higher than the large plunger and fill the dashpot through the small plunger opening. Move the large plunger occasionally during filling to allow air to escape. To check for trapped air once the dashpot is filled, install the small plunger, close the dash pot needle, and operate the large plunger while holding the small plunger. The small plunger should react instantly to any movement of the large plunger. Any lag in small plunger movement indicates there is air in the dashpot or a leak past the needle, solenoid bypass, or the plungers. To purge the air, open the needle, hold the small plunger in place, and operate the large plunger. To check the condition of the dashpot, close the bypass and the needle completely, push the small plunger down as far as it will go, and time how long it takes to recenter. It should take more than 50 seconds to travel 0.125" A shorter time indicates excessive leakage past the needle or plungers and the dashpot should be repaired or replaced. After any maintenance on the dashpot, it is important to perform the governor adjustment tests of section 7 to bring the governor back to optimum performance. 8.1 0. Links and Pins Monthly adjustments: Lubricate links and pivot pins with a light machine oil. Annual adjustments: Check links and pins for wear or binding. Use anew pin to check holes in links for wear, and use a new link '\-Vith the proper sized mating hole to check the condition of the pins. Replace pins and links as required. Check bearings in the linkage, on the shafts, and in the control panel for any roughness and replace as required. Lubricate bearings as required. Check gears for wear and proper meshing. 8.11. Restoring Cable Annual adjustments: Lubricate restoring cable sheaves and rod ends at the servomotor connection. Unscheduled adjustments: Disassemble sheaves and inspect sheaves and 'cable. Replace sheaves if the pulley is worn or if the bearings are rough. 32 8.12. Hydraulic System Daily adjustments: Check the level of oil in the sump and the actuator tank and add oil or charge the pressure tank with air as required. Weekly adjustments: Switch the lead pump to lag and vice versa Monthly adjustments: Switch the strainers and clean or replace the filter element If the pumps are equipped with hour meters, note the run time. Compare the run time to the previous month's readings and investigate any large deviation. Annual adjustments: Before scheduled maintenance, send a sample of the governor oil to the laboratoiy for analysis. If analysis shows filtration is required, drain and filter the oiL When the oil is drained, clean the oil sump and actuator tank with lint free rags and squeegee, inspect, and repaint as required. Check the condition of the float valve disk, seat, float, and float arm for any damage or wear. Check the condition of the float, the cable, and the sheaves of level switches for wear and free operation. After the system is refilled, check the operation of the pump unloader valve. Check the operation of the pressure relief valves on the pumps and actuator tank. Relief valves on the actuator tank should be set to operate at a pressure no higher than the maximum allowable working pressure for the tank. The pump relief valves should be set to operate at a slightly lower pressure than the actuator tank relief valve. This is to prevent the pumps from continuing to fill the actuator tank if high pressure occurs in the system. Check the calibration and operation of the pressure and level switches and reset as required. Check annunciation where applicable. With wicket gates blocked, time the pumping cycle for each pump, noting the length of time the pump is on, the rise of the oil level in the actuator tank, and the length of time between pumping cycles. Compare the time to previous readings. If the pump is taking longer to reach operating pressure or is pumping more frequently, check for leaks in the system. 8.13. Generator Air Brake Valve Annual adjustments: Check the manual and solenoid operation of the valve. Lubricate pivot points with light machine oil. Clean the airline filter. Biannual adjustments: Disassemble and remove all rust spots with a fine grade emery cloth (320 to 500) and crocus cloth. Lap the valve seats if required. 33 8.14. Permanent Magnet Generator (PMG) or Speed Signal Generator (SSG) Annual adjustments: Inspect the speed S\vitches and drive gears for wear. Lubricate pivot pins and check speed switch bearings. Check the setting and operation of the speed switches. Check the insulation between PMG or SSG housing and the supporting frame by measuring the resistance from the housing to ground with a meggar. Replace or repair the insulating gasket as required Check the voltage output of the PM G. Unscheduled adjustments: Replace the main drive bearings of the PMG or SSG. If necessary, remagnetize the PMG field follo\\oing the procedure in section 5. 8.15. Position and Limit Switches Annual adjustments: Check the operation and settings of the gate limit, the speed changer position, and the gate position switches and adjust as required. Clean the contacts as required. Check the drive gears for wear and proper meshing. Check annunciation where applicable. 8.16. Shutdown Solenoids Annual adjustments: Check the operation of the solenoids for binding or sticking when tripped and reset. Check the settings to ensure that the complete shutdov..n solenoid closes the wicket gates completely and the partial shutdown solenoid brings the gates to the speed no load setting. When the solenoids are reset, make sure that the linkage does not prevent the gates from going to 100 percent Inspect the solenoid for any signs of overheating or other damage. Check the condition of electrical connections and auxiliary contacts. 8.17. Speed Changer, Gate Limit Motors, and Remote Position Indicators Annual adjustments: Operate motors and check for excessive vibration or noise. Replace bearings as required. Check electrical connections and motor brushes. Check the operation of the position indicators for any sticking or binding and check the correlation between the transmitter and receiver. Check gears for wear and proper meshing. Check the clutch adjustment. 9. TROUBLESHOOTING A well-maintained mechanical governor will provide years or trouble free service, but eventually there will be problems. Friction and misadjustment are the biggest cause of problems. It would be impossible to address every possible problem. Some of the more common problems and the most likely causes are discussed below. 34 9.1. Hunting Hunting is an unstable condition in which the governor can't maintain frequency at an acceptable level when operating off line. Some movement of the wicket gates and frequency wander is normal for a mechanical governor, but if the frequency wander exceeds 0.2 hertz peak to peak or if the automatic synchronizer can't put the unit on line, it is considered excessive. On-line hunting (the wicket gates move back and forth) can occur, but is fairly uncommon. Off-line hunting is usually the first and possibly the only sign of a problem with a governor. Off- line hunting is a symptom of a variety of problems. The most common cause of off-line hunting is misadjustment of the dashpot. If the dashpot needle is too far open, there is not enough compensation and the governor will hunt Ideally, the best solution is to perform the governor tests as outlined in section 7. If that is not possible, the dashpot needle should be slowly closed until the hunting stops. This will allow the unit to be put on line but probably won't be an optimum adjustment for the dashpot. The tests of section 7 should be scheduled to readjust the governor. If the dashpot needle is completely closed and the unit is still hunting, there is probably a problem ·with the dashpot. If the dashpot had been removed and refilled with dashpot oil, there may be air in the lower chamber of the dash pot. Remove the dashpot and work the air out as described in paragraph 8.9. If air in the dashpot has been ruled out, the dashpot should be checked for excessive leakage by the test described in paragraph 8. 9. If the leakage is excessive with the dashpot needle closed, also close the bypass needle completely to check for leakage past the solenoid valve. If the leakage is still excessive, the dashpot must be replaced or rebuilt. Excessive friction can also cause hunting. It is often possible to reduce the hunting caused by friction by closing the dashpot needle. This may allow the unit to be put on line, but the governor response will be slow and irregular. The governor response tests of section 7 can help show friction by an irregular response instead of the normal smooth curve. While the test may show that there is friction in the system, fmding the source of friction can be difficult. If the irregular response is seen only in one direction, the friction is probably in the restoring mechanism. Because the restoring cable is rigidly attached to the servomotor, movement in the direction that the servomotor pulls the cable may be smooth. Movement in the other direction may be affected by friction because the cable is pulled by only a large hanging weight. The friction may be in the cable sheaves or in any of the linkage attached to the restoring cable in the cabinet. Other sources of friction may be the pilot valve, dashpot, pivot pins, ball head, main valve, and the vvicket gate operating mechanism. On-line hunting is not very common. Once a unit is on line, the actual speed of the unit can't change. Any hunting on line is the result of a bad signal from the PMG (the most common cause) or a hydraulic problem. The most likely cause of on-line hunting is a broken or damaged drive pin. If a drive pin is broken or damaged, the speed of the PMG will change slightly every revolution, causing the \vicket gates to move. An example of a hydraulic problem causing on- line hunting is a restoring ratio setting that is too large. If the main valve is allowed to move to far before the pilot valve bushing resets, the hydraulic system can become unstable. This is very uncommon, and on most mechanical governors, it is not possible to set the restoring ratio high enough for this to occur on line. 35 9.2. Inability to Reach Full Speed The inability of a unit to reach 100 percent speed usually happens after major maintenance on the governor. This problem is usually the result of a misadjusted speeder rod on a Woodward governor or the speed setting screw on a Pelton governor. If adjusting the speed rod or the set screw· doesn't bring the unit to normal speed, the problem may be in the ball head or the gate limit Damage to the ball head, such as a broken spring, may cause the pilot valve to center at a lower or higher speed than normal. If the gate limit is out of adjustment, the gate may be restricted from opening to the speed no load position. The alignment procedure in section 4 should be used to realign the gate limit 9.3. Inability to Reach Full Load The most common cause of a unit not being able to reach full load is the gate limit being out of adjustment The procedure in section 4 should be followed to align the gate limit. Another cause of a unit not being able to reach full load is misadjustment of the shutdown solenoid. On a Woodward governor, the shutdovm rods that act on the gate limit shaft are adjusted with acorn nuts to determine how far the gate limit is driven on a shutdown. If these nuts are too high, they will prevent the gates from opening. 9.4. Wicket Gates Sticking Midrange Wicket gates sticking when the governor is calling for a chan.ge is usually not a function of the governor. This is usually the result of friction in the wicket linkage or in the wicket gates themselves, or may be the result of marginally sized servomotors. 36 18. Exciters and Voltage Regulators 18.1 General Exciters and voltage regulators comprise excitation systems which provide appropriate DC excitation for the field of generators and synchronous motors. Excitation systems may be rotating or static. 18.2 Maintenance Schedule for Exciters and Voltage Regulators Some components of excitation systems (e.g., transformers, circuit breakers, protective relays, annunciators, and buswork) may require maintenance similar to that described in like sections of this document. However, excitation system manufacturer maintenance requirements supersede requirements specified in these sections. Automatic voltage regulator performance testing ("alignment") is a specialty, requiring specialized training and unique equipment as well as knowledge of current power system stability requirements. It is recommended that qualified staff in the Hydroelectric Research and Technical Services Group (D-8450) perform these tests. Recommended Maintenance or Test Interval Reference Preventive maintenance Per manufacturer's Manufacturer's instruction manuals recommendations Automatic voltage regulator 5 years Western Electricity Coordinating (AVR) and power system Council Controls Working Group stabilizer (PSS) fY'VG) Recommendations Policy performance testing Contact the Controls Team of the Hydroelectric Research and Technical Services Group, D-8450, 303-445-2309 Infrared scan Annually Reclamation Recommended Practice 28 20.2 Maintenance Schedule for Fuses Some fuse failures are self evident. Loss of meter indication or control circuit operation may indicate a blown (open) fuse. Other fuses that are critical to equipment operation may be monitored and their opening alarmed. However, some fuse operation cannot be detected remotely and should be assessed by regular maintenance. It may be as simple as looking for the "fuse operated" indicator on the fuse, or it may require checking with an ohmmeter. Failure to do so may result in more significant failure leading to an outage. Recommended Maintenance or Test Interval Review equipment ratings 5 years Remove, inspect, and 3-6 years check Check fuse mounting clips, etc. Visual inspection and Annually infrared scan, while loaded or immediately thereafter. 21. Generators and Large Motors 21.1 General Reference NERC Planning Standard FAC-009-1 NFPA 708, 15.2.3 Annex H.2j Annex 1.1 NFPA 708, 15 NFPA 708, 20.17 Annex H Generators produce electrical energy from mechanical power transmitted from the turbine. Large motors drive pumps to move water. Generators and large motors included in this section are synchronous machines performing the primary function of the power or pumping plant. Small motors are covered in section 24, "Motors." 21.2 References and Standards Maintenance references and standards from which the recommendations are drawn are numerous: • Manufacturers instruction books • FIST Volume 3-1, Testing Solid Insulation of Electrical Equipment • Power O&M Bulletin No. 19 -Maintenance Schedules and Records • IEEE Standard (Std.) 432-1992, Guide for Insulation Maintenance for Rotating Electric Machinery (5 horsepower [hpj to 10,000 hp) 30 • IEEE Std. 95-1997, Recommended Practice for Insulation Testing of Large AC Rotating Machinery with High Direct Voltage • IEEE Std. 43-2000, Recommended Practice for Testing Insulation Resistance of Rotating Machinery • Conditions Rating Procedures/Condition Indicator for Hydropower Equipment, U.S. Anny Corps of Engineers • Handbook to Assess the Insulation Condition of Large Rotating Machines, Volume 16, Electric Power Research Institute • Electric Generators, Power Plant Electrical Reference Series, Volume 1, EPRI • Inspection of Large Synchronous Machines, L Kerszenbaum • Test Procedure for Synchronous Machines, IEEE 115-1983 • Guide for Operation and Maintenance of Hydrogenerators, IEEE Std. 492- 1974 21.3 Maintenance Schedule for Generators and Large Motors Note: . See J\ppendix B ir:i this docum~nt Maintenance or Test Recommended Interval Preventive maintenance and inspections No standard recommended interval. Machine specific PM according to site operating conditions. Also, see Appendix B. Stator winding-physical inspection During 1-, 2Y2-, and 5-year warranty inspections; thereafter, during major maintenance outages but not to exceed 5years. Stator winding • high voltage DC ramp test 3 to 5 years and after prolonged maintenance outage. Stator winding-insulation resistance polarization index (Megger®) Stator winding-AC Hipot test Stator winding'-partial discharge measurements (on line monitoring with partial discharge equipment) 31 Performed in lieu of HVDC ramp test At factory and as an acceptance test. Non- routine thereafter but may be used to verify insulation integrity before and/or after stator winding repair. Nonroutine. Performed if problems are suspected. Continued Stator winding • black out test Stator winding -ozone measurement Stator winding -wedge tightness measurements Stator winding -power factor measurements (Doble) Stator core -physical inspection Stator core-core magnetizing test Rotor -physical inspection Rotor -insulation resistance polarization (Megger®) Rotor -AC pole drop test Thrust and upper guide bearing insulation test 22. Governors 22.1 General Nonroutine. Periormed when deterioration is suspected. Nonroutine. Periormed when deterioration detected. During 1-, 21;2-, and 5-year warranty inspections; thereafter, periormed after rotor is removed (particularly if unit in operation for 20-25 years without rewedging). Nonroutine. May be periormed in conjunction with other generator condition tests. During 1-, 21;2-, and 5-year warranty inspections; thereafter, during major maintenance outages but not to exceed 5 years. Nonroutine. Should be periormed prior to rewind or if core has been damaged. During major maintenance outages but not to exceed 5 years. Nonroutine. Periormed when deterioration is suspected. Nonroutine. Periormed when deterioration is suspected. Annually per FIST Volume 5-11. Governors control generator power and frequency output by regulating water flow to the turbine. Governors may be mechanical type or electrohydraulic type having electronic controls. New digital governors substitute digital control circuits for analog electronic controls of older electrohydraulic governors. Mechanical governor maintenance is fully described in FIST Volume 2-3, Mechanical Governors for Hydraulic Units. Mechanical maintenance requirements for all types of governors are identified in FIST Volume 4-lA, Maintenance Scheduling for Mechanical Equipment. The electrical maintenance schedule below supplements the.'le mechanical maintenance requirements. 32 22.2 Maintenance Schedule for Governors Recommended Maintenance or Test Interval Preventive maintenance Per manufacturer's recommendations Control system alignment 5 years 23. Ground Connections 23.1 General Reference Manufacturer's instruction manuals Reclamation Recommended Practice Equipment grounding is an essential part of protecting staff and equipment from high potential caused by electrical faults. Equipment grounding conductors are subject to failure due to corrosion, loose connections, and mechanical damage. Grounding may also be compromised during equipment addition and removal or other construction-type activities. Periodically verifying grounding system integrity is an important maintenance activity. 23.2 Maintenance Schedule for Ground Connections in sutistidonS,$wttchyards Recommended Maintenance or Test Interval Reference Visual inspection, Annually PEB No. 26 tighten connectors 24. Motors(< 500 hp) 24.1 General Motors of this type drive pumps, valves, gates, and fans. They are usually induction motors and are generally less than 500 hp but may be somewhat larger. Critical motors should routinely be tested. 33 10.3 Low Voltage (600 V and Less [480 V] Draw Out Air Breaker Maintenance Schedule Recommended Maintenance or Test Interval Reference Review equipment ratings 5 years NERC Planning Standard . FAC-009-1 Preventive maintenance and Per manufacturer's Manufacturer's Instruction inspection recommendations, Book 1-3 years maximum NFPA 798, 8.4 Annex H.4(d) Insulation testing and 1 "3 years per FIST FIST Volume 3-16 overcurrent and fault trip 3 years maximum NFPA 708, 8.4.6.4 seHings and testing Annex H Table H.4(d) Annex Tablel.1 Visual inspection and infrared Annually NFPA 708,20.17 scan, while loaded or immediately thereafter 10.4 Medium Voltage (601-15 kV Rated) Air and Air Blast Breaker Maintenance Schedule Recommended Maintenance or Test Interval Reference Review equipment ratings 5 years NERC Planning Standard FAC-009-1 Inspection and preventive 1-3 years NFP A 708, 8.4 maintenance, lube, clean, Annex H Table H.2(e) adjust, align control Manufacturer's instruction mechanism manuals Appendix A, this document Overcurrent trip settings and Annually or FIST Volume 3-16 testing, test all trips 2,000 operations NFP A 708, 20.1 0 (3-year maximum) Annex H.2(e) Annex 1.1 Contact resistance Per manufacturer's Per manufacturer's measurement instructions instructions Breaker timing Per manufacturer's Per manufacturer's (Motion analyzer) instructions instructions Either Hipot (to ground and 3-6 years NFPA 70B between phases) OR Annex H Table H.2(e) Doble test 3-6 years NFPA 708 Doble Field Test Guide Visual inspection and Annually NFPA 708,20.17 infrared scan, while loaded or immediately thereafter 19 11. Communication Equipment This document does not defme maintenance of communication equipment used in power system operation. Refer to communication system operation and maintenance requirements included in these documents: • Bureau of Reclamation Radio Communication Systems -Management and Use-Guidelines 07-01. Maintenance requirements are given in section 14. • Department of the Interior -Departmental Manual -Radio Communications Handbook (DM377) Information regarding operation and maintenance of Reclamation communication systems may be found at the Reclamation intranet site: http:/ /intra. usbr.gov/telecom. 12. Control Circuits 12.1 General Control circuits (usually 125 Vdc, 250 Vdc, or 120 Vac) provide the path for all control functions for major equipment in the powerplant. Reliability of these circuits is paramount. Although tested during commissioning, these circuits can become compromised over time through various means: • Modifications and construction work which unintentionally break circuit integrity or introduce wiring errors. • Age and deterioration of wiring rendering the system nonfunctional. • Connections that become loose. • Failure of individual control and protection devices due to misuse, old age, or inadvertent damage. Verifying the integrity of the control devices and-interconnecting wiring requires a "functional test" of these circuits. Functional testing of control circuits may be considered completed in the course of normal plant operation. However, control circuits that rarely are used should be functionally tested on a periodic basis. 12.2 Maintenance Schedule for Control Circuits Recommended Maintenance or Test Interval Functional test control circuits 3·6 years 23 Reference NFPA 708 under specific equipment and Appendix H • Molded case circuit breakers are usually located in low voltage distribution panels and in control boards. These are typically 120-volts alternating current (Vac), 125-volts direct current (Vdc), 240-Vac, and 480-Vac breakers for control, protection, and auxiliary power. Molded case breakers in panel boards should not be loaded more than 80% of rating per NFPA 70B, 11-2. • Low voltage air breakers are usually located in motor starter cabinets, motor control centers, station service switchgear, or similar enclosures. These are typically 480 Vac for auxiliary power. • Medium voltage circuit breakers are generally located in station-service metal clad switchgear or in separate enclosures as unit breakers. Examples are 4160-Vac station service, 11.95-kV and 13.8-kV unit breakers. These breakers may be air, air blast, vacuum, or SF6. • High voltage circuit breakers are located in separate breaker enclosures, either indoors or outdoors. These are oil, air-blast, or SF6 breakers. Examples are 115-kV and 230-kV breakers located in the switchyard. • Extra high voltage (EHV) circuit breakers are not addressed in this FIST volume. Reference the manufacturer's instruction books. Most breaker maintenance (except infrared scanning) must be performed with equipment de-energized. 1 0.2 Molded Case Breaker Maintenance Schedule, Feeder and Critical Control anti Protection 'Breakers Recommended Maintenance or Test Interval Reference Review equipment ratings 5 years NERC Planning Standard FAC-009-1 Visual inspection 3-6 years NFPA 708, 20.1 0.2.4 Annex H.4F Table 1.1 Mechanical operation 2 years NFPA 708, 13.10 and by hand Table H.4(f) Annex I, Table 1.1 Test critical breakers with 3-6 years NFPA 708,20.10 current source 300% ol FIST 3-16 rating; test fault trip Annex I, Table 1.1 Infrared scan, while lpaded Annually NFPA 708, 20.17 or immediately thereafter 18 18. Exciters and Voltage Regulators 18.1 General Exciters and voltage regulators comprise excitation systems which provide appropriate DC excitation for the field of generators and synchronous motors. Excitation systems may be rotating or static. 18.2 Maintenance Schedule for Exciters and Voltage Regulators Some components of excitation systems (e.g., transformers, circuit breakers, protective relays, annunciators, and buswork) may require maintenance similar to that described in like sections of this document. However, excitation system manufacturer maintenance requirements supersede requirements specified in these sections. Automatic voltage regulator performance testing ("alignment") is a specialty, requiring specialized training and unique equipment as well as knowledge of current power system stability requirements. It is recommended that qualified staff in the Hydroelectric Research and Technical Services Group (D-8450) perform these tests. Recommended Maintenance or Test Interval Reference Preventive maintenance Per manufacturer's Manufacturer's instruction manuals recommendations Automatic voltage regulator 5 years Western Electricity Coordinating (AVR) and power system Council Controls Working Group stabilizer (PSS) (WG) Recommendations Policy performance testing Contact the Controls Team of the Hydroelectric Research and Technical Services Group, 0-6450, 303-445-2309 Infrared scan Annually Reclamation Recommended Practice 28 June 2003 Page 13 of63 Fist 3-31 TRANSFORMER DIAGNOSTICS The ratio of total accumulated gas C02/CO = 2326/199 = 11.7. The ratio of increase C02/CO = 1317/ 23 =57. Neither of these ratios is low enough to cause concern. This shows that the thermal fault is not close enough to the cellulose insulation to cause heat degradation of the insulation. The large increase in C02 could mean an atmospheric leak. The fault is probably a bad connection on a bushing bottom, a bad contact or connection in the tap changer, or a problem with a core ground. These problems are probably all reparable in the field. Any of these problems can cause the results revealed by the Duval Triangle diagnosis above. These are areas where a fault will not degrade cellulose insulation which would cause the C02/CO ratio to be much lower than what was obtained. For information to arrive at a probable fault see FIST Volume 3-30, section 4.4. 5.4 Expertise Needed A Transformer Expert should be consulted if a problematic trend is evidenced by a number of DGAs. The transformer manufacturer should be consulted along with DGA lab personnel as well as others experienced in transformer maintenance and diagnostics. Never make a diagnosis based on one DGA; a sample may have been mishandled or mislabeled either in the field or lab. 6. OIL PHYSICAL/CHEMICAL TESTS When sending oil samples to a laboratory for DGA, one should also specify other tests that reveal oil quality. 6.1 Transformer Oil Tests That Should Be Performed Annually With the Dissolved Gas Analysis 6.1.1 Dielectric Strength. This test measures the voltage at which the oil electrically breaks down. The test gives an indication of the amount of contaminants (water and oxidation particles) in the oil. DGA laboratories typically use ASTM D-1816. Using the D-1816 test, the minimum oil breakdown voltage is 20 kilovolts (kV) for transformers rated less than 288 kV and 25 kV for transformers 287.5 kV and above. If a dielectric strength test falls below these numbers, the oil should be reclaimed. Do not base any decision on one test result, or on one type of test; look at all the information from several DGA tests and review trends before making any decision. The dielectric strength test is not extremely valuable; moisture in combination with oxygen and heat will destroy cellulose insulation long before the dielectric strength of the oil has indicated anything is going wrong. See Transformer Maintenance Guide, by J.J. Kelly, S.D. Myers, Page 14 of63 June 2003 Fist 3-31 TRANSFORMER DIAGNOSTICS R.H. Parrish, S.D. Myers Co 1981 [5]. The dielectric strength test also reveals nothing about acids and sludge. The tests explained below are much more important in that regard. 6.1.2 Interfacial Tension (1FT). This test, ASTM D-971-91, Standard Test Method for Interfacial Tension of Oil Against Water by the Ring Method [6], is used by DGA laboratories to determine the interfacial tension between the oil sample and distilled water. The oil sample is placed in a beaker of distilled water at a temperature of 25 • £. The oil will float because its specific gravity is less than that of water. There should be a distinct line between the two liquids. The 1FT number is the amount of force (dynes) required to pull a small wire ring upward a distance of l centimeter through the water/oil interface. A dyne is a very small unit of force equal to 0.000002247 pound. Good clean oil will make a very distinct line on top of the water and give an 1FT number of 40 to 50 dynes per centimeter of travel of the wire ring. As oil ages, it is contaminated by tiny particles (oxidation products) of the oil and paper insulation. Particles on top of the water extend across the water/oil interface line which weakens the surface tension between the two liquids. Particles in oil weaken interfacial tension and lower the IFT number. IFT and acid number (see below) together are an excellent indication of when oil needs to be reclaimed. It is recommended the oil be reclaimed when the 1FT number falls to 25 dynes per centimeter. At this level, the oil is very contaminated and must be reclaimed to prevent sludging, which begins around 22 dynes per centimeter. See FIST Volume 3-5, Maintenance of Liquid Insulation: Mineral Oils and Askarels [7}. If oil is not reclaimed, sludge will settle on windings, insulation, cooling surfaces, etc., and cause loading and cooling problems. This will greatly shorten transformer life. It Acidity-' 0.8 ... There is a definite relationship between acid number, the 1FT, and years-in-service. The accompanying curve (figure 5) shows the relationship and is found in many publications. Notice that the curve shows \ \ Normal Service v I II) 0.6 ~ the normal service limits both for the 1FT and the acid number. ' Limit for Acidity ~. !f I I " Tension / ~ ~ -r-Normal Servlc~-(! -r--., Limit for IFT ~ i"oo.. I I .J...-' 3 6 9 12 15 Years in Service ;::! z "'C 0.4 '(j < 0.2 ~ 0 18 Figure 5.-SeiVIce Limits for Transformer 011. June 2003 Fist 3-31 TRANSFORMER DIAGNOSTICS Page 15 of63 6.1.3 Acid Number. Acid number is the amount of potassium hydroxide (KOH) in milligrams (mg) that it takes to neutralize the acid in 1 gram (gm) of transformer oil. The higher the acid number, the more acid is in the oil. New transformer oils contain practically no acid. Oxidation of insulation and oils form acids as the transformer ages. Oxidation products form sludge particles in suspension in the oil which rains (precipitates out) inside the transformer. The acids attack metals inside the tank and form soaps (more sludge). Acid also attacks cellulose and accelerates insulation degradation. Sludging has been found to begin when the acid number reaches 0.40; it is obvious that the oil should be reclaimed long before it reaches 0.40. It is ·recommended that the oil be reclaimed when the acid number reaches 0.20 mg KOH/gm [5]. As with all others, this decision must not be based on one DGA test; look for a rising trend in the acid number each year. Plan ahead and begin budgeting for reclaiming the oil before the acid number reaches 0.20. 6.1.4 Furans. Furans are a family of organic compounds which are formed by degradation of paper insulation [8]. Overheating, oxidation, acids, and decay caused by high moisture with oxygen accelerate the destruction of insulation and form furanic compounds. As with dissolved gases, increases in furans between DGA tests are important When furans become greater than 250 parts per billion (ppb), the oil should be reclaimed; paper insulation is being deteriorated and transformer life reduced at a high rate. Look at the 1FT and acid number in conjunction with furans. Furanic content in the oil is especially helpful in estimating remaining life in the paper insulation, particularly if several prior tests can be compared and trends established. Also see also section 17.3 for more on furans. 6.1.5 Oxygen. Oxygen (02) must be watched closely in DGA tests. Many experts and organizations, including EPRI, believe that above 2,000 ppm, oxygen in the oil greatly accelerates paper deterioration. This becomes even more critical with moisture above safe levels. See the Moisture section below and FIST, Volume 3-30, table 12 for moisture levels. Under the same temperature conditions, cellulose insulation in low oxygen oil will last 10 times longer than insulation in high oxygen oil [5]. It is recommended that if oxygen reaches 10,000 ppm in the DGA, the oil should be de-gassed and new oxygen inhibitor installed (see below). High atmospheric gases (02 and nitrogen [N2]) normally mean that a leak has developed in a bladder or diaphragm in the conservator. If there is no conservator and pressurized nitrogen is on top of the oil, expect to see high nitrogen but not high oxygen. See FIST Volume 3-30 [ 1] for how to check for leaks. Oxygen comes only from leaks and from deteriorating insulation. 6.1.6 Oxygen Inhibitor. Test for oxygen inhibitor every 3 to 5 years with the annual DGA test Moisture is destructive to cellulose and even more so in the presence of oxygen. Acids are formed that attack the insulation and Page 16 of 63 Fist 3-31 TRANSFORMER DIAGNOSTICS June 2003 metals which form soaps and more acids, causing a viscious cycle. Oxygen inhibitor is key to extending the life of transformers. The inhibitor currently used is Ditertiary Butyl Paracresol (DBPC). This works similar to a sacrificial anode in grounding circuits; oxygen attacks the inhibitor instead of the cellulose insulation. As this occurs and the transformer ages, the inhibitor is used up and needs to be replaced. Replacement of the inhibitor generally requires that the oil also be treated [5). The ideal amount ofDBPC is 0.3% by total weight of the oil, which is given on the transformer nameplate [9). 6.1.7 Oil Power Factor. Power factor indicates the dielectric loss (leakage current associated with watts loss) of the oiL This test can be performed by DGA laboratories. It may also be done by Doble testing in the field. A high power factor indicates deterioration and/or contamination from byproducts such as water, carbon, or other conducting particles, including metal soaps caused by acids attacking transformer metals, and products of oxidation. DGA labs normally test oil power factor at 25 • € and 100 • €. Information in Doble Engineering Company Reference Book on Insulating Liquids and Gases RBIL-391, 1993 [ 1 0] indicates the in-service limit for power factor is less than 0.5% at 25 • €. If the power factor is greater than 0.5% and less than 1.0%, further investigation is required; the oil may require replacement or Fuller's earth filtering. If the power factor is greater than 1.0% at 25 •C, the oil may cause failure of the transformer; replacement or reclaiming of the oil is required immediately. Above 2%, oil should be removed from service and replaced because equipment failure is imminent. The oil cannot be reclaimed. 6.1.8 Moisture. Moisture, especially in the presence of oxygen, is extremely hazardous to transformer insulation. Recent EPRl studies show that oxygen above 2,000 ppm dissolved in transformer oil is extremely destructive. Each DGA and Doble test result should be examined carefully to see if water content is increasing and to determine the moisture by dry weight (MJDW) or percent saturation in the paper insulation. When 2% M/DW is reached, plans should be made for a dry out. Never allow the M/DW to go above 2.5% in the paper or 30% oil saturation before drying out the transformer. Each time the moisture is doubled in a transformer, the life of the insulation is cut by one-half. Keep in mind that the life of the transformer is the life of the paper, and the life of the paper is extended by keeping out moisture and oxygen. For service-aged transformers rated less than 69 kV, results of up to 35 ppm at 60 oc are considered acceptable. For 69 kV through 230 kV, a DGA test result of20 ppm at 60 °C is considered acceptable. For greater than 230 kV, moisture should never exceed 12 ppm at 60 °C. However, the use of absolute values fo.r water does not always guarantee safe conditions, and the percent by dry weight should be determined. See table 12, "Doble Limits for In-Service Oils," in section 4.6.5 of FIST, Volume 3-30 [1]. If values are higher than these limits, the oil should be processed. Reclamation specifies that manufacturers dry new 26. Relays and Protection Circuits 26.1 General Secti9n .11.4 9f!4<fW es~ept Eiectri~ity CQ()r(lit}~ting <Z9pncil (W~CGJMJ~imum Opi1-a1tn···. Rtili(if)iJitytf#e.n } ·&if< ::·thaH~;~~hs 1 sJe-¥n ~h~li P!Q\da?for · •'' · .· • fJ • ·· ·.<\'!' ,.,.,, · ··.•<;·' •·.· •> •. ·\•c·· F_: ; •••• •/<·:';•·'·'<· .l.v.;v ·:•' ••. '.•: ,.,, ... •.-'•Y • , · . peri()(fictestifigofprote9tive ~ys .. ·· .. ·.·• a*df7IIleoia1Jfuti§ij,sc~etrfes which impact the reliability and security of the intercon1leet&l system operation." Protective relays monitor critical electrical and mechanical quantities and initiate emergency shutdown whenever they detect out-of-limits conditions. Protective relays must operate correctly when abnormal conditions require and must not operate at any other time. Electrical protective relays are calibrated with settings derived from system fault and load studies. Initial settings are provided when relays are installed or replaced. However, electrical power systems change as new generation and transmission lines are added or modified. This may mean that relay settings are no longer appropriate. Outdated relay settings can be hazardous to personnel, to the integrity of the powerplant and power system, and to the equipment itself. Therefore, it is necessary to periodically conduct a fault and load study and review protective relay settings to ensure safe and reliable operation. Fault and load studies and relay settings are provided by the Electrical Design Group (D-8440) at 303-445-2850. Field-initiated changes to relay settings should be verified by this group. Protective relays currently in use in Reclamation include electro-mechanical, solid-state, and microprocessor-based packages. Calibration and maintenance recommendations differ from type to type because of their different design and operating features. Calibration: This process usually includes removal of the relay from service to a test environment. Injecting current and/or voltage into the relay and observing the response according to the manufacturer's test procedure verifies the recommended settings. Calibration of electro-mechanical relays is recommended frequently since operating mechanisms can wear and get out of adjustment. Calibration of solid-state and microprocessor-based relays is recommended less frequently since there are fewer ways for them to get out of calibration. Relay Functional Test: This process verifies that the protective ou~uts of the relay (e.g., contact c1osures) actually operate as intended. This can be accomplished as part of the calibration procedure in most cases, but relay functional testing should be verified according to the maintenance schedule. Protective relays operate into protection circuits to accomplish the desired protective action. Similar to control circuits, protection circuit integrity may be compromised by construction, modifications, deterioration, or inadvertent damage. A compromised protection circuit may not provide the system and plant protection desired. Periodic functional testing is recommended to ensure the integrity of protection circuits. 35 Protection Circuit Functional Testing: This process verifies that the entire protective "trip path" from protective relay through circuit breakers (or other protective equipment) is intact and functional. This requires actually operating the entire circuit to verify correct operation of all components. Protective circuit functional testing is accomplished as follows: • Conduct a Job Hazard Analysis. • Verify that testing will not disrupt normal operation or endanger staff or equipment. • With lockout relays reset, initiate lockout relay trip with the protective device contact. 3 • Verify the lockout relay actually tripped from the protective relay action. Verify that circuit breakers actually tripped (or other protective action occurred) from the lockout relay action. • Activate the lockout relay from each protective device. After the first full test of lockout relay and breakers, it may be desirable to lift the trip bus from the lockout relay so as not to repeatedly trigger the lockout-a meter may be substituted to verify contact initiation. Caution: Do not forget to reconnect the trip bus to the lockout relay when testing is complete. Where functional testing of ALL protection circuits is unfeasible, testing of the most critical protection circuits and devices is still recommended. Reclamation standard design for lockout relay and circuit breaker control circuits includes the use of the red position/coil status indicator light to monitor the continuity of the circuit through the trip coil. These lights should be lit when the lockout relay is in the "Reset" position or when the breaker is closed. If the light is not lit, this may indicate a problem with the coil integrity which should be addressed immediately. 3 It is recommended that the protective device actually be operated where possible for best assurance. The ideal functional test is to actually change input quantities (e.g., instrument transformer secondary injection) to the protective device to thoroughly test the entire protection path. However, it may be necessary to simulate contact operation with a 'jumper" when device activation is not possible. 36 26.2 Maintenance Schedule for Relays and Protection Circuits Recommended Maintenance or Test Interval Reference FauiVIoad study and 5 years Reclamation recalculate settings Recommended Practice NERC FAC-009-1 Electro-mechanical relays Upon commissioning and NFPA7()8, 8.9.7 and Calibration and functional every 2 years 20:·111:$ testing Annextilbte 1. 1 Per manufacturer's instructions Fisf3-8 < -M '' WECC Std. 11.4 Solid-state relays Upon commissioning NFPA 708, 8.9. 7 and Calibration and functional 1 year after commissioning 2o.lo.a testing and every 3 years Annexit:it>Je 1.1 Per manufacturer's instructions FistS.:a WECC Std. 11.4 Microprocessor relays Upon commissioning Reclamation Calibration and functional 1 year after commissioning Recommended testing and every 8-10 years Practice Per manufacturer's instructions Fist ~a WECC Std. 11.4 Protection circuit functional Immediately upon FIST Volume 3-8 test, including lockout installation and/or upon any NFPA 708 relays changes in wiring and AnnexTable H.4(c) every 3-6 years Manufacturer's instruction manuals PEBNo. 6 Check red light lit for lockout Daity1 Reclamation relay and circuit breaker Recommended coil continuity Practice Lockout relays 5 years Power Equipment Cleaning and lubrication Bulletin No. 6 and Manufacturer's instructions 1 In staffed plants, in conjunction with daily operator control board checks. Otherwise, check each visit to the plant. 37 3. Arresters 3.1 General Lightning or surge arresters provide protection for important equipment from high-energy surges. These arresters are static devices which require fairly infrequent maintenance. Most maintenance must take place while the associated circuit is de-energized. However, crucial visual inspections and infrared scans can take place while energized. 3.2 Maintenance Schedule for Arresters Recommended Maintenance or Test Interval Review equipment rating 5 years Visual inspection with Quarterly to semi- binoculars annually Clean insulatpr and check 3-6 years connections Ambient dependent Doble test (power tre-3-6 years quency dielectric loss, Ambient dependent direct current [DC] insulation resistance, power factor) Replace all $iliCon carbide arresters with metal oxide As soon as possible varistor type Infrared scan AnnuaUy 4. Batteries and Battery Chargers 4.1 General Reference NERC Planning Standard FAC-009-1 NFPA 708, 8.9.2.1 Annex I Table l. 1 Manufacturer's instruction manuals Doble Test Data Reference Book NFPA 708, 8.9.2.2 Annex I Table 1.1 PEB No:12 Maru.lfacWrer's teroriunendation NFPA 708, 20.17 Battery systems provide "last resort" power for performing communication, alarm, control, and protective functions when other sources of power fail. Battery system maintenance should have highest priority. Computerized, oriline battery monitoring systems can greatly reduce maintenance required on battery systems and actually improve battery reliability and increasebattery life. Reclamation has had positive experience with these systenis, and they should be considered to supplement a maintenance program. Battery chargers, important to the health and readiness of battery systems, require regular maintenance as well. 11 4.2 Maintenance Schedute -Flooded, Wet Cell, Lead Acid Batteries Maintenance or Recommended Test Interval Reference Visual inspection Monthly FIST Volume 3-6, Table 1 Battery float Shift (charger meter) FIST Volume 3-6, Table 1 voltage Monthly overall battery voltage Record on POM with digital meter compare with Form 133A charger meter Cell float voltage Monthly, pilot cells with digital FIST Volume 3-6, Table 1 meter Record on POM Quarterly, all cells Form 133A Specific gravity Monthly, pilot cells FIST Volume 3-6, Table 1 Quarterly, 10 percent(%) of cells Record on POM Annually, all cells Form 133A Temperature Monthly (pilot cell) FIST Volume 3-6, Table 1 Quarterly (10% of all cells) Record on POM Form 133A Connection Annually, all connections FIST Volume 3-6, Table 1 resistance Record on POM Form 134A Capacity testing 5 years, annually if capacity FIST Volume 3-6 less than 90% IEEE 450-1995 Safety equipment Monthly, test all wash devices FIST Volume 3-6 inspection and inspect all safety equipment IEEE 450-1995 Infrared scan cells Annually NFPA 708 20.17 and connections Battery monitoring According to manufacturer's Manufacturer's instruction system recommendations manual 12 be scheduled, staffed, and budgeted. They may be scheduled on a time, meter, or number of operationsbasis but may be planned to coincide with scheduled equipment outages. Since these activities are predictable, some offices consider them "routine maintenance" or "preventive maintenance." Some examples are Doble testing, meggering, relay testing, circuit breaker trip testing, alternating current (AC) high-potential (Hipot) tests, high voltage direct current (HVDC) ramp tests, battery load tests. • Diagnostic Testing-Activities that involve use of test equipment to assess condition of equipment after unusual event<> such as faults, fires, or equipment failure/repair/replacement or when equipment deterioration is suspected. These activities are not predictable and cannot be scheduled ·because they are required after a forced outage. Each office must budget contingency funds for these events. Some examples are Doble testing, AC Hipot tests, HVDC ramp tests, partial discharge measurement, wedge tightness, core magnetization tests, pole drop tests, turns ratio, and core ground tests. This FIST volume addresses scheduling of maintenance activities in the first two categories. It does not address followup work generated by routine maintenance or maintenance testing, nor does it address diagnostic testing (with a few exceptions). Also, maintenance staff may be used for other activities such as improvements and construction, but this guide does not address these activities. PEB No. 29, Electrical Testing Synopses, addresses standard tests for electrical equipment in Reclamation powerplants. 1.3~2 lnfrared Scanning Annual infrared scans of electrical equipment are required by NFPA 70B, 18-17.5. Throughout this FIST volume, infrared (IR) scanning is recommended as a regular maintenance procedure. Infrared scanning and analysis have become an essential diagnostic tool throughout all industries and have been used in Reclamation to detect many serious conditions requiring immediate corrective action. Several forced outages already have been avoided. Infrared scanning is non-intrusive and is accomplished while equipment is in service. It can be used not only for electrical equipment but also to detect mechanical and structural problems. Therefore, infrared scanning is HIGHLY recommended as a regularly scheduled maintenance procedure. Effective infrared scanning and analysis require the following: • The scanning equipment (IR camera and accessories) must be high quality and correctly maintained and calibrated. • The IR camera operator must be trained to use the equipment and deal with complicating issues such as differing ernissivities of surfaces and reflectivity. Certified Levell Thermographer (e.g., Academy of IR Thermography) credentials, or higher, are recommended. • The IR system operator must be able to analyze results using state-of-the-art software critical to successful interpretation of problems. 6 Field offices with adequate resources may find it possible to achieve professional results by operating a local IR program. Others may find it more cost effective to hire a contractor or use the resources in the Hydroelectric Research and Technical Services Group (D-8450). Call303-445-2300 for more information. 1.3.3 Fault and Load Flow Studies/Equipment Ratings Electrical power systems change as new generation and transmission lines are added or modified. Changes also occur as new equipment is added or upgraded inside the powerplant. This may mean that load ratings ofvarious equipment and interruptingratings of breakers and ruses are no longer adequate. Underrated or misapplied electrical equipment can be hazardous to personnel, to the integrity of the powerplant and power system, and to the equipment itself. Therefore, it is necessary to periodically conduct faull and load studies and to review equipment ratings for adequacy (continuous current, momentary current, momentary voltage, basic impulseirisulationlevel [BIL}, current interrupting ratings, etc;) and for coordination of protective relays, circuit breakers, and fuses to ensure safe and reliable operation. North American Electric Reliability Council (NERC) Planning Standards FAC-009-1 also requires periodic fault and load flow studies. Requirements for reviewing equipment ratings are indicated where appropriate in the maintenance schedules in this volume. These studies are typically performed by the Electrical Systems Group, D-8440, 303-445-2850. 1.4 Maintenance Schedules and Documentation Complete, accurate, and current documentation is essential to an effective maintenance program. Whether performing preventive, predictive, or reliability centered maintenance, keeping track of equipment condition and maintenance- performed and planned-is critical. Maintenance recommendations contained in this volume should be used as the basis for establishing or refining a maintenance schedule. Recommendations can be converted into Job Plans or Work Orders in MAXIMO or another maintenance management system. Once these job plans and work orders are established, implementation of well-executed maintenance is possible. The maintenance recordkeeping system must be kept current so that a complete maintenance history of each piece of equipment is available at all times. This is important for planning and conducting an ongoing maintenance program and provides documentation needed for the Power O&M Reviews (section 1.7). Regular maintenance and emergency maintenance must be well documented as should special work done during overhauls and replacement. The availability of up-to-date drawings to management and maintenance staff is extremely important. Accurate drawings are very important to ongoing maintenance, testing, and new construction; but they are essential during 7 31.3 Station/Distribution Transformers Under 500 kVA4 31.3.1 General Station and distribution transformers generally operate at relatively low voltages and power ratings. They provide step-down power to supply plant auxiliary loads-for example, a 480 -240/120-Vac transformer that supplies power to auxiliary lighting panels. 31.3.2 Maintenance Schedule for Station and Distribution Transformers Recommended Maintenance or Test Interval Review equipment ratings 5 years Infrared scan, while loaded Annually Doble test if oil-filled 3-6 years Dissolved gas analysis if Annually oil-filled 31.4 Instrument Transformers 31.4.1 General Reference NERC Planning Standard FAC-009-1 NFPA 708, 20.17 FIST Volume 3-30 Reclamation Recommended Practice FIST Volume 3-30 NFPA 708, 9.2.8 Instrument transformers convert power system level voltages and current to levels safe to feed meters and other low voltage and current devices. Voltage or potential transformers generally have output in the 240/120-Vac range, while current transformers have output in the 2.5-to 5-ampere range. Voltage transformers may be integral to other equipment or stand alone. Typically, current transformers are integral to other equipment (circuit breakers, transformers) but occasionally may be stand alone (e.g., 500-kV switchyard at Grand Coulee). Over the course of time, instrument transformers (particularly current transformers) may become overburdened with the addition of more devices in the secondary circuit. This may lead to saturation during a fault which may cause the relay to misoperate. Periodically, measuring secondary burden and comparing it to the transformer rating will indicate if this is a problem. Instrument transformer secondary wiring always should be checked for integrity after any work that may have disrupted these circuits. Instrument transformers that are oil-filled will fail catastrophically and cause hazards to workers if not maintained properly. Any oil leak should trigger immediate Doble testing and replacement planning. 4 kV A = kilovoltampere. 41 31.4.2 Maintenance Schedule for Instrument Transformers Recommended Maintenance or Test Interval Reference Review equipment ratings 5 years NERC Planning Standard Burden measurements 5 years FIST Volume 3-8 Doble test if oil-filled 5 years Reclamation Recommended Practice Visual inspection Annually Reclamation Recommended Practice Infrared scan Annually NFPA 708,20.17 31.5 Dry-Type Power Transformers-500 kVA and Larger 31.5.1 General Dry-type power transformers are air cooled, having no liquid insulation. Typical applications include station service and excitation system transformers. 31.5.2 Maintenance Schedule for Dry-Type Power Transformers Recommended Maintenance or Test Interval Reference Review equipment ratings 5 years NERC Planning Standard FAC-009-1 Infrared scan Annually NFPA 708, 20.17 FIST Volume 3-30 Temperature alarm check Annually NFPA 708, 9.3 Annex H.2(c) FIST Volume 3-30 Visual inspection/cleaning Annually NFPA 708, 9.3 Annex H.2(c) FIST Volume 3-30 Check fan operation Annually NFPA 708, 9.3 Annex H.2(c) FIST Volume 3-30 Clean fans and filters Annually NFPA 708, 9.3 Annex H.2(c) . FIST Volume 3-30 Turns ratio test 3-6 years or if NFPA 708, 9.3 problems are . Annex H.2(c) suspected NFPA 708, 20.11 Megger® windings or 3-6 years or NFPA 708 Hi pot when problem is Annex H.2(c) suspected NFPA 708, 9.2.9 and 20.9 42 31.6 Oil-Filled Power Transformers 31.6.1 General Oil-filled transformers generally deliver power to and from the main units of the facility-for example, generator step-up transformers. These transformers are generally located outside the building in a transformer bay or in a switchyard. These transformers may be two-winding or more and include autotransformers. 31.6.2 Maintenance Schedule for Oil-Filled Power Transformers Recommended Maintenance or Test Interval Reference Review equipment 5 years NERC Planning Standard ratings FAC-009·1 Preventive maintenance Per manufacturer's Manufacturer's instruction recommendations manuals FIST Volume 3-30 Transformer physical Annually NFPA 70B, 9.2 inspection Annex H FIST Volume 3·30 Bushings -visual Quarterly and Doble Bushing Field Test Guide inspection 3·5 years IEEE P62·1995 FIST Volume 3-30 Bushings -check oil Weekly FIST Volume 3·30 level Bushings -cleaning 3-5 years FIST Volume 3·30 Transformer and 3-5 years FIST Volume 3-2 bushings -Doble test (6 months to 1 year for Doble Bushing Field Test Guide suspect bushings} IEEE P62-1995, 6.2 FIST Volume 3-30 Transformer and Annually NFPA 70B, 20.17 bushings -infrared scan FIST Volume 3-30 Insulating oil -DGA, Annually alter first year NFPA 70B, 9.2.9.4 physical, and of operation FIST Volume 3-5 chemical tests FIST Volume 3-30 Core -Megger® test If DGA indicates IEEE P62·1995, 6.1.5 NFPA 70B, 9.2 Annex H.2(b} FIST Volume 3-30 Leakage reactance, If problems are FIST Volume 3-30 Tums Ratio tests, indicated by other tests FIST Volume 3-31 SFRA test Cooling fans -inspect Annually FIST Volume 3-30 and test Oil pumps and motors -Annually FIST Volume 3-30 inspect and test 43 27. SCADA Systems 27.1 General Supervisory Control and Data Acquisition (SCADA) systems are computer-based, real-time control systems for power and water operations. Since these systems are in operation continuously and are in many ways self-diagnosing, regular maintenance and testing is not necessary except as recommended by the manufacturer. However, circuits that are infrequently used may require periodic functional testing to ensure they will be operational when the need arises. Security requirements affecting SCAD A are dictated by documents such as Presidential Decision Directive 63: Critical Infrastructure Protection, May 22, 1998, and Office of Management and Budget (OMB) Circular A-130, Appendix III, Security of Federal Automated Resources, February 8, 1996. Periodic audits, Critical Infrastructure Protection Plans (CIPP), and regularly scheduled security training are important requirements of SCAD A security. 27.2 Maintenance Schedule for SCADA Systems Recommended Maintenance or Test Interval Preventive maintenance Per manufacturer's recommendations Functional test circuits 3-6 years Failure mode tests Annually Security -audit 3 years Security-CIPP updated 2 years Security-training Annually Uninterruptible power Annually supply test 28. Security Systems 28.1 General Reference Manufacturer's instruction manuals Reclamation Recommended Practice Reclamation Recommended Practice OMB Circular A-130, Appendix Ill Presidential Decision Directive 63 Public Law (P.L.) 100-235, Computer Security Act of 1987 Reclamation Recommended Practice Security systems at powerplants are critical for protection of Reclamation personnel, the public, and facility equipment. Most security systems are site 38 ·, - ' .-. specific including many different manufacturers of cameras, receivers, card key systems, gates, gate controls, and other types of equipment. Therefore, it is impemtive that personnel at each plant understand and follow manufacturers' instructions for maintenance and testing the particular equipment installed. 29. Switches, Disconnect -Medium and High Voltage 29.1 General When open, disconnect switches permit isolation of other power system components, thus, facilitating safety during maintenance procedures. Disconnect switches may be manually or motor operated and, in some cases, may integrate fuse protection. (See section 20 on fuses). · 29.2 Maintenance Schedule for Disconnect Switches Recommended Maintenance or Test Interval Review equipment ratings 5 years Preventive maintenance Per manufacturer's recommendations and per Appendix C Visual inspection Semi-annual Infrared scan, while Annually loaded 30. Transducers/Meters 30.1 General Reference NERC Planning Standard FAC-009-1 Manufacturer's instruction manuals AppendixC NFPA 708, 8.7 Annex H.2(f) FIST Volume 4-18, AppendixC NFPA 708,20.17 Transducers convert data collected in one format into electrical signals used by meters and computerized monitoring and control systems. Accuracy of transduced signals is important to alarm and control functions. Examples of transduced data include: • Bearing oil level or temperature read by a meter or scanning equipment • Megawatt or megavars as input to the SCAD A system 39 30.2 Maintenance Schedule for Transducers Maintenance or Test Recommended Interval Bfif!mff~; Calibration 30.3 Maintenance Schedule for Meters Meters indicate, and sometimes record, electrical and mechanical quantities for operator information. Some meters also transmit stored data to Supervisory Control and Data Acquisition (SCAD A) or other systems. Accuracy of meter indication is important to ensure correct power and water systems operation. Maintenance or Test Calibration/inspection 31. Transformers 31.1 General Recommended Interval 3~Ryea~,vyitt) trC'lrt$ducers @,rt?wQ~11 Pr<iblems' fire s!Jspeqt~d Reference NFPA 7(j B, 8.9.7 Transformers convert electrical power from one voltage level to another. Transformer reliability is essential to the continued delivery of the facility's services. 31.2 References and Standards Maintenance references and standards from which the recommendations are drawn are numerous: • Manufacturers' instruction books • Doble Transformer Maintenance and Test Guide • IEEE Std. 62-1995 • FIST Volume 3-30, Transformer Maintenance • FIST Volume 3-31, Transformer Diagnostics • NFPA 70B-Recommended Practices for Electrical Equipment Maintenance • Transformers: Basics, Maintenance, and Diagnostics (Reclamation manual) 40 19. Fire Detection, Fire Fighting Equipment, and Alarm Systems 19.1 General Fire detection and alarm systems provide indication and warning of fire in the facility. They are crucial to safety of personnel and the public. Correct operation may also minimize damage to equipment by an early response. Regular maintenance of systems in unstaffed facilities is particularly important because O&M staff are not usually present to detect problems. 19.2 Maintenance Schedule for Fire Detection, Fire Fighting Equipment, and Alarm Systems Recommended Maintenance or Test Interval Reference All circuits -functional test Annually-staffed facility NFPA 72,7-3.1 Quarterly-unstafted facility Visual inspection of detection Annually -staffed facility NFPA 72, 7-3.1 and control equipment (fuses, Weekly-unstafled facility interfaces, lamps, light emitting diodes, primary power supply) Visual inspection -batteries Monthly NFPA 72, 7-3.1 Lead acid battery 30-minute Monthly NFPA 72, 7-3.1 discharge and load voltage test Ni Cad battery 30-minute Annually NFPA 72, 7-3.1 discharge and load voltage test Other maintenance 1 Per NFP A recommendations NFPA 72,7 Fire hoses Annually unrolled and NFPA 72, 7-3.1 inspected Fire extinguisher maintenance Annually (site specific) NFPA 72 1 NFPA 72 7 is revised regularly, and requirements change frequently. Reference the latest version of the standard for the latest requirements. 20. Fuses 20.1 General Fuses provide power and control circuit protection by interrupting current under certain overload and fault conditions. 29 3. Arresters 3.1 General Lightning or surge arresters provide protection for important equipment from high-energy surges. These arresters are static devices which require fairly infrequent maintenance. Most maintenance must take place while the associated circuit is de-energized. However, crucial visual inspections and infrared scans can take place while energized. 3.2 Maintenance Schedule for Arresters Rec~mended Maintenance or Test Interval Review equipment rating 5 years Visual inspection with Quarterly to semi· binoculars annually Clean ins!JI?tor and check 3·6 years connections Ambient dependent Doble test (power fre· 3-6 years quency dielectric loss, Ambient dependent direct current {DC] insulation resistance, power factor) Replac~ .all silicon carbide arresters with metal oxide As soon as possible varistor type · · · Infrared scan Annually 4. Batteries and Battery Chargers 4.1 General Reference NERC Planning Standard FAC-009·1 NFPA 708, 8.9.2.1 Annex I Table 1.1 Manufacturer's instruction manuals Doble Test Data Reference Book NFPA 708, 8.9.2.2 Annex I Table 1.1 PEBNo;'•12 Mariilf.aeiUr~r's reoomm~hdation NFPA 708,20.17 Battery systems provide "last resort" power for performing communication, alarm, control, and protective functions when other sources of power faiL Battery system maintenance should have highest priority. Computerized, online battery monitoring systems can greatly reduce maintenance required on battery systems and actually improve battery reliability and increase battery life. Reclamation has had positive experience with these systems, and they should be considered to supplement a maintenance program. Battery chargers, important to the health and readiness of battery systems, require regular maintenance as welL 11 4.2 Maintenance Schedule-Flooded, Wet Cell, Lead Acid Batteries Maintenance or Recommended Test Interval Reference Visual inspection Monthly FIST Volume 3·6, Table 1 Battery float Shift (charger meter) FIST Volume 3-6, Table 1 voltage Monthly overall battery voltage Record on POM with digital meter compare with Form 133A charger meter Cell float voltage Monthly, pilot cells with digital FIST Volume 3-6, Table 1 meter Reqord on POM Quarterly, all cells Form 133A Specific gravity Monthly, pilot cells FIST Volume 3-6, Table 1 Quarterly, 10 percent(%) of cells Record on POM Annually, all cells Form 133A Temperature Monthly (pilot cell) FIST Volume 3·6, Table 1 Quarterly (1 0% of all cells) Record on POM Form 133A Connection Annually, all connections FIST Volume 3-6, Table 1 resistance Record on POM Form 134A Capacity testing 5 years, annually if capacity FIST Volume 3-6 less than 90% IEEE 450-1995 Safety equipment Monthly, test all wash devices FIST Volume 3-6 inspection and inspect all safety equipment IEEE 450-1995 Infrared scan cells Annually NFPA 708 20.17 and connections Battery monitoring According to manufacturer's Manufacturer's instruction system recommendations manual 12 14. Cranes, Hoists, and Elevators 14.1 General Cranes, hoists, and elevators are important to operation and maintenance of the facility. Proper maintenance of cranes and hoists will ensure they are ready for service which will reduce time and cost of maintaining other equipment. Maintaining elevators is important to the convenience and safety of staff, visitors, and the public. Also, elevators must be inspected periodically by a certified elevator inspector. Maintenance of these types of equipment is important to the safety ofeve~yone .. gte,vators must be certified by a State71icei1se(t itisp&tor annually in most St&tes. 14.2 Maintenance Schedule for Cranes, Hoists, and Elevators Mechanical maintenance of cranes, hoists, and elevators is covered in FIST Volume 4-lA, Maintenance Scheduling of Mechanical Equipment. Only the electrical components are covered here. Maintenance or Test Recommended Interval Inspect motors, controls, wiring Annually 15. Electrical Drawings 15.1 General Reference FIST Volume 2~10 FIST Voh.illlefi1A Electrical drawings, especially 1-lines, switching diagrams, control and protection schematics, and wiring diagrams, are the most important references for safety and O&M of a facility. Ideally, these drawings will be kept current with all modifications and replacements to plant equipment. Every effort must be made to keep key electrical drawings up to date to avoid risk to equipment and staff. Key electrical drawings should be accessible to all O&M personneL 15.2 Maintenance Schedule for Electrical Drawings Maintenance or Test Recommended Interval Key control and protection schematics Current and avanable Key wiring diagrams Current and available 1-line, 3-lines, tripping, switching diagrams Current and available Relay data sheets Current and available 25 16. Emergency Lighting 16.1 General Reliable plant emergency lighting is essential for personnel safety. 16.2 Maintenance Schedule for Emergency Lighting Recommended Maintenance or Test Interval Preventive maintenance Per manufacturer's recommendation Functional test Monthly (30 seconds) Functional test Annually (1 Y2 hours) 17 ~· En_gine Generators 17.1 General Reference Manufacturer's instruction manuals NFPA 101, 5.9.3 NFPA 101, 5.9.3 Engin,~g~n~wiors are critical sys~ atpo'.\'erplants, dams, ~doth~r water- rehi~f~~li~~;_p:pey D1~$t be ~~~~-~~t~ied 'regli.Iar!ytoeiisl1J:e·they willperfomi ·.~· expeeted. ':Manufactlirei a.na NFPA st;mdams<~howd oo followed. Engine generators proyide es~ential power to supply critical1()ads in the event of loss ofnorinlil powersoutce. SJ)ilh\;ay.oroutletgates/valves may need to be operated. for. water release purposes with engine generator power. Powerplant criticall<)ads such as sump pumps,fire putJ1ps,·and battery chargers also are dependent on reliable power. Engine generators also may be used to power unit auxiliaries .and the generator excitation system for blacks tart generators. assigned to restore the power system after a blackout. 26 Home Read Tutorials Testimonials About Us Product Directory Order Status lAtMidl Bome >Tutorial Index> Battery Tutorial Battery Tutorial You have most likely heard the term K.I.S.S. (Keep It Simple, Stupid). I am going to attempt to explain how lead acid batteries work and what they need without burying you ·with a bunch of needless technical data. Actually I have found that battery manufacturer's data will vary somewhat so I must generalize in some cases. The commercial use ofthe lead acid battery is over 100 years old. The same chemical principal is being used to create energy that our Great, Great, Grandparents may have used. If you can grasp the basics you will have fewer battery problems and will gain greater battery performance, reliability, and longevity. I suggest you read the entire tutorial, however I have indexed all the information for a quick read and easy reference. A battery is like a piggy bank. If you keep taking out and putting nothing back you soon will have nothing. Present day chassis battery power requirements are huge. Look at today' s vehicle and all the electrical devices that must be supplied. Electronics require a source of reliable power. Poor battery condition can cause expensive electronic component failure. Did you know that the average auto has 11 pounds of wire in the electrical system? Look at RVs and boats with all the electrical gadgets that require power. I can remember when a trailer or motor home had a single 12-volt house battery. Today it is standard to have 2 or more house batteries powering inverters up to 4000 watts. Average battery life has become shorter as energy requirements have increased. Life span depends on usage; 6 months to 48 months, yet only 30% of all batteries actually reach the 48-month mark. A :Few Basics The Lead Acid battery is made up of plates, lead, and lead oxide (various other elements are used to change density, hardness, porosity, etc.) with a 35% sulfuric acid and 65% water solution. This solution is called electrolyte which causes a chemical reaction that produce electrons. When you test a battery with a hydrometer you are measuring the amount of sulfuric acid in the electrolyte. If your reading is low, that means the chemistry that makes electrons is lacking. So where did the sulfur go? It is resting to the battery plates and when you recharge the battery the sulfur returns to the electrolyte. 1. Safetv 2. l;)attervlY12Q~,ll~~12-C'vcle____<ll1d Stauing 3. ~VeLCill Gel-CeiL and Absorbed Glass Mat LAGMJ 4. CCA. CA. AH iiDd RC~ vvhat's that <!llabout~ 5. Battery rvlaintenanC_f 6. Batt_ITL T esti_ug 7. Selecting and Bu\'im2. a New Batte!): 8. f,?~merv Life anc!_E~rforl]1ance 9. l;3atten::_ChargirJg 10. _Batterv QQ's 11. Batlm:J)on'ts 1. We must think safety when we are working around and with batteries. Remove all jewelry. After all you don't want to melt your watchband while you are wearing the watch. The hydrogen gas that batteries make when charging is very explosive. I have had 2 batteries blow up and drench me in sulfuric acid. That is no fun. This is a good time to use those safety goggles that are hanging on the wall. Sulfuric Acid eats up clothing and you may want to select Polyester clothing to wear, as it is naturally acid resistant. I just wear junk clothes, after all Polyester is so out of style. When doing electrical work on vehicles it is best to disconnect the ground cable. Just remember you are messing with corrosive acid, explosive gases and 1 OO's amps of electrical current. 2. Basically there are two types of batteries; starting (cranking), and deep cycle (marine/golf cart). The starting battery (SLI starting lights ignition) is designed to deliver quick bursts of energy (such as starting engines) and have a greater plate count. The plates will also be thinner and have somewhat different material composition. The deep cycle battery has less instant energy but greater long-term energy delivery. Deep cycle batteries have thicker plates and can survive a number of discharge cycles. Starting batteries should not be used for deep cycle applications. The so-called Dual Purpose Battery is only a compromise between the 2 types ofbatteries. 3. Wet Cell (flooded), Gel Cell, and Absorbed Glass Mat (AGM) are various versions ofthe lead acid battery. The wet cell comes in 2 styles; serviceable, and maintenance free. Both are filled with electrolyte and I prefer one that I can add water to and check the specific gravity of the electrolyte with a hydrometer. The Gel Cell and the AGM batteries are specialty batteries that typically cost twice as much as a premium wet cell. However they store very well and do not tend to sulfate or degrade as easily or as easily as wet cell. There is little chance of a hydrogen gas explosion or corrosion when using these batteries; these are the safest lead acid batteries you can use. Gel Cell and some AGM batteries may require a special charging rate. I personally feel that careful consideration should be given to the AGM battery technology for applications such as Marine, RV, Solar, Audio, Power Sports and Stand-By Power just to name a few. If you don't use or operate your equipment daily; this can lead premature battery failure; or depend on top-notch battery performance then spend the extra money. Gel Cell batteries still are being sold but the AGM batteries are replacing them in most applications. There is a little confusion about AGM batteries because different manufactures call them different names; some of the popular ones are sealed regulated valve, dry cell, non spillable, and sealed lead acid batteries. In most cases AGM batteries will give greater life span and greater cycle life than a wet cell battery. SPECIAL NOTE about Gel Batteries: It is very common for individuals to use the term GEL CELL when referring to sealed, maintenance free batteries, much like one would use Kleenex when referring to facial tissue or "Xerox machine" when referring to a copy machine. Be very careful when specifYing a battery charger, many times we are told by customer they are requiring a charger for a Gel Cell battery and in fact the battery is not a Gel Cell. AGM: The Absorbed Glass Matt construction allows the electrolyte to be suspended in close proximity with the plates active material. In theory, this enhances both the discharge and recharge efficiency. Actually, the AGM batteries are a variant of Sealed VRLA batteries. Popular usage high performance engine starting, power sports, deep cycle, solar and storage battery. The AGM batteries we sell are typically good deep cycle batteries and they deliver best life performance if recharged before the battery drops below the 50 percent discharge rate. If these AGM batteries are discharged to a rate of 100 percent the cycle life will be 300 plus cycles and this is true of most AGM batteries rated as deep cycle batteries. GEL: The gel cell is similar to the AGM style because the electrolyte is suspended, but different because technically the AGM battery is still considered to be a wet cell. The electrolyte in a GEL cell has a silica additive that causes it to set up or stiffen. The recharge voltages on this type of cell are lower than the other styles of lead acid battery. This is probably the most sensitive cell in terms of adverse reactions to over- voltage charging. Gel Batteries are best used in VERY DEEP cycle application and may last a bit longer in hot weather applications. If the incorrect battery charger is used on a Gel Cell battery poor performance and premature failure is certain. 4. CCA, CA, AH and RC what are these all about? Well these are the standards that most battery companies use to rate the output and capacity of a battery. Cold cranking amps (CCA) is a measurement ofthe number of amps a battery can deliver at 0 oF for 30 seconds and not drop below 7.2 volts. So a high CCA battery rating is good especially in cold weather. CA is cranking amps measured at 32 degrees F. This rating is also called marine cranking amps (MCA). Hot cranking amps (RCA) is seldom used any longer but is measured at 80 o F. Reserve Capacity (RC) is a very important rating. This is the number of minutes a fully charged battery at 80 oF will discharge 25 amps until the battery drops below 10.5 volts. An amp hour (AH) is a rating usually found on deep cycle batteries. If a battery is rated at 100 amp hours it should deliver 5 amps for 20 hours, 20 amps for 5 hours, etc. 5. Battery Maintenance is an important issue. The battery should be cleaned using a baking soda and water mix; a couple of table spoons to a pint of water. Cable connection needs to be clean and tightened. Many battery problems are caused by dirty and loose connections. A serviceable battery needs to have the fluid level checked. Use only mineral free water. Distilled water is best. Don't overfill battery cells especially in warmer weather. The natural fluid expansion in hot weather will push excess electrolytes from the battery. To prevent corrosion of cables on top post batteries use a small bead of silicon sealer at the base of the post and place a felt battery washer over it. Coat the washer with high temperature grease or petroleum jelly (Vaseline), then place cable on the post and tighten. Coat the exposed cable end with the grease. Most folks don't know that just the gases from the battery condensing on metal parts cause most corrosion. 6. Battery Testing can be done in more than one way. The most popular is measurement of specific gravity and battery voltage. To measure specific gravity buy a temperature compensating hydrometer and measure voltage, use a digital D.C. Voltmeter. A good digital load tester may be a good purchase if you need to test batteries sealed batteries. You must first have the battery fully charged. The surface charge must be removed before testing. If the battery has been sitting at least several hours (I prefer at least 12 hours) you may begin testing. To remove surface charge the battery must experience a load of 20 amps for 3 plus minutes. Turning on the headlights (high beam) will do the trick. After turning off the lights you are ready to test the battery. J ~tateofChar~e J/_~P~~i~c Gravi; !/ Volta;e --.. ll2~J~~; r-:'-'---'---'10-'0..:..:;<J<.....:o _;_;.:_:;:; 1.:_:..._-'--1.-'2-6 5~-'---'--~: l12. 7 '16. 3 l *75% ·/ 1.225 112.4 !16.2 *Sulfation of Batteries starts when specific gravity falls below 1.225 or voltage measures less than 12.4 (12v Battery) or 6.2 (6 volt battery). Sulfation hardens the battery plates reducing and eventually destroying the ability of the battery to generate Volts and Amps. Load testing is yet another way of testing a battery. Load test removes amps from a battery much like starting an engine would. A load tester can be purchased at most auto parts stores. Some battery companies label their battery with the amp load for testing. This number is usually 112 of the CCA rating. For instance, a 500CCA battery would load test at 250 amps for 15 seconds. A load test can only be performed if the battery is near or at full charge. The results of your testing should be as follows: Hydrometer readings should not vary more than .05 differences between cells. Digital Voltmeters should read as the voltage is shown in this document. The sealed AGM and Gel-Cell battery voltage (full charged) will be slightly higher in the 12.8 to 12.9 ranges. If you have voltage readings in the 10.5 volts range on a charged battery, that indicates a shorted cell. If you have a maintenance free wet cell, the only ways to test are voltmeter and load test. Most of the maintenance free batteries have a built in hydrometer that tells you the condition of 1 cell of 6. You may get a good reading from 1 cell but have a problem with other cells in the battery. When in doubt about battery testing, call the battery manufacturer. Many batteries sold today have a toll free number to call for help. 7. Selecting a Battery -When buying a new battery I suggest you purchase a battery with the greatest reserve capacity or amp hour rating possible. Of course the physical size, cable hook up, and terminal type must be a consideration. You may want to consider a Gel Cell or an Absorbed Glass Mat (AGM) rather than a Wet Cell if the application is in a harsher environment or the battery is not going to receive regular maintenance and charging. Be sure to purchase the correct type of battery for the job it must do. Remember an engine starting battery and deep cycle batteries are different. Freshness of a new battery is very important. The longer a battery sits and is not re-charged the more damaging sulfation build up there may be on the plates. Most batteries have a date of manufacture code on them. The month is indicated by a letter 'A' being January and a number '4' being 2004. C4 would tell us the battery was manufactured in March 2004. Remember the fresher the better. The letter "i" is not used because it can be confused with #1. Battery warranties are figured in the favor of battery manufactures. Let's say you buy a 60-month warranty battery and it lives 41 months. The warranty is pro-rated so when taking the months used against the full retail price of the battery you end up paying about the same money as if you purchased the battery at the sale price. This makes the manufacturer happy. What makes me happy is to exceed the warranty. Let me assure you it can be done. 8. Battery life and performance -Average battery life has become shorter as energy requirements have increased. Two phrases I hear most often are "my battery won't take a charge, and my battery won't hold a charge". Only 30% of batteries sold today reach the 48-month mark. In fact 80% of all battery failure is related to sulfation build-up. This build up occurs when the sulfur molecules in the electrolyte (battery acid) become so deeply discharged that they begin to coat the battery's lead plates. Before long the plates become so coated that the battery dies. The causes of sulfation are numerous. Let me list some for you. • Batteries sit too long between charges. As little as 24 hours in hot weather and several days in cooler weather. • Battery is stored without some type of energy input. • "Deep cycling" an engine starting battery. Remember these batteries can't stand deep discharge. • Undercharging of a battery, to charge a battery (lets say) to 90% of capacity will allow sulfation of the battery using the 10% ofbattery chemistry not reactivated by the incomplete charging cycle. • Heat of 100 plus F., increases internal discharge. As temperatures increase so does internal discharge. A new fully charged battery left sitting 24 hours a day at 110 degrees F for 30 days would most likely not start an engine. • Low electrolyte level -battery plates exposed to air will immediately sulfate. • Incorrect charging levels and settings. Most cheap battery chargers can do more harm than good. See the section on battery charging. • Cold weather is also hard on the battery. The chemistry does not make the same amount of energy as a warm battery. A deeply discharged battery can freeze solid in sub zero weather. • Parasitic drain is a load put on a battery with the key off More info on parasitic drain will follow in this document. There are ways to greatly increase battery life and performance. All the products we sell are targeted to improve performance and battery life. An example: Let's say you have "toys"; an ATV, classic car, antique car, boat, Harley, etc. You most likely don't use these toys 365 days a year as you do your car. Many of these toys are seasonal so they are stored. What happens to the batteries? Most batteries that supply energy to power our toys only last 2 seasons. You must keep these batteries from sulfating or buy new ones. We sell products to prevent and reverse sulfation. The PulseTecb products are patented electronic devices that reverse and prevent of sulfation. Also Battery Equaliser a chemical battery additive has proven itself very effective in improving battery life and performance. Other devices such as Solar TrickleCllMger~ are a great option for battery maintenance. Parasitic drain is a load put on a battery with the key off Most vehicles have clocks, engine management computers, alarm systems, etc. In the case of a boat you may have an automatic bilge pump, radio, GPS, etc. These devices may all be operating without the engine running. You may have parasitic loads caused by a short in the electrical system. If you are always having dead battery problems most likely the parasitic drain is excessive. The constant low or dead battery caused by excessive parasitic energy drain will dramatically shorten battery life. If this is a problem you are having, check out the Priority Start and Marine Priority Start to prevent dead batteries before they happen. This special computer switch will turn off your engine start battery before all the starting energy is drained. This technology will prevent you from deep cycling your starting battery. 9. Battery Charging-Remember you must put back the energy you use immediately. If you don't the battery sulfates and that affects performance and longevity. The alternator is a battery charger. It works well if the battery is not deeply discharged. The alternator tends to overcharge batteries that are very low and the overcharge can damage batteries. In fact an engine starting battery on average has only about 10 deep cycles available when recharged by an alternator. Batteries like to be charged in a certain way, especially when they have been deeply discharged. This type of charging is called 3 step regulated charging. Please note that only special SMART CHARGERS using computer technology can perform 3 step charging techniques. You don't find these types of chargers in parts stores and Wal-Marts. The first step is bulk charging where up to 80% of the battery energy capacity is replaced by the charger at the maximum voltage and current amp rating of the charger. When the battery voltage reaches 14.4 volts this begins the absorption charge step. This is where the voltage is held at a constant 14.4 volts and the current (amps) declines until the battery is 98% charged. Next comes the Float Step. This is a regulated voltage of not more than 13.4 volts and usually less than 1 amp of current. This in time will bring the battery to 100% charged or close to it. The float charge will not boil or heat batteries but will maintain the batteries at 100% readiness and prevent cy.cling during long term inactivity. Some gel cell and AGM batteries may require special settings or chargers. 10. Battery Do's • Think Safety First. • Do read entire tutorial • Do regular inspection and maintenance especially in hot weather. • Do recharge batteries immediately after discharge. • Do buy the highest RC reserve capacity or AH amp hour battery that will fit your configuration. 11. Battery Don'ts • Don't forget safety first. • Don't add new electrolyte (acid). • Don't use unregulated high output battery chargers to charge batteries. • Don't place your equipment and toys into storage without some type of device to keep the battery charged. • Don't disconnect battery cables while the engine is running (your battery acts as a filter). • Don't put off recharging batteries. • Don't add tap water as it may contain minerals that will contaminate the electrolyte. • Don't discharge a battery any deeper than you possibly have to. • Don't let a battery get hot to the touch and boil violently when charging. • Don't mix size and types ofbatteries. There are many points and details I have not written about but I wanted to keep this as short and simple as possible. Further information can be found at the links below. If you are aware of sites with good battery maintenance information please let me know. Shop for ... Batteries Battery Chargers .Inverters Battery Restoratio11 Balterv Accessories Fw.::J Treatments seward Hydro Power Plant Inspection 0 ....-I LARSEN BAY HYDROELECTRIC PROJECT ANNUAL MAINTENANCE INSPECTION April 22, 23, and 24, 2003 The inspection participants were Art Copoulos, Project Manager (Alaska Energy Authority), Stan Sieczkowski, Operations Manager (FDPP A), and Karl Livingston, Plant Operator, (Larsen Bay). 1.0 PROJECT DESCRIPTION Facilities The Larsen Bay Hydroelectric Project is located on Humpy Creek about Y2 mile from the City of Larsen Bay at Latitude 153 58' 16" and Longitude 57 32' 19". The City of Larsen Bay is located on the Kodiak Island, about 60 air miles from the City of Kodiak. The community has approximately 45 permanent residential houses in use and seasonal influx of cannery employees. This run-of-river project has a 140-ft long, 14-ft. high dam, and a small reservoir with minimal water storage. The spillway at elevation 1676 ft., is 30 feet wide. The 6,062-ft. penstock (3,584 ft. 18 inch PVC and 2,416 ft. 16 inch steel) is buried in the road from the dam to the power plant. A 4-inch line from the penstock in the powerhouse feeds the domestic water tank. The powerhouse has one generator rated at 475 KW. The turbine, at elevation 1006.25-ft., has two nozzles and deflectors and operates at 290 psi, with approximately 670 feet of head. There are two high voltage transformers and a set of high voltage disconnect switches in the hydro distribution system. There is a small maintenance shed and material storage yard near the power plant. The Alaska Energy Authority owns the Larsen Bay Hydroelectric Project. The project is operated and maintained by the City of Larsen Bay, for the state. The Project went into commercial operation on July 5, 1991. 2.0 INSPECTION OF FACILITIES Dam and Reservoir The storage reservoir has silt building up and requires routine flushing. It was cleaned in Oct. 2001 and Oct. 2002. A rock trap was installed about 10 feet in front of the penstock intake in 2001. Also, a debris trap was installed in the side flow stream. The reservoir was not cleaned during this outage. There was about 3 inches of silt build up in the reservoir. Alders need to be removed from around the reservoir. The spillway wire gabion baskets need to be monitored for sagging and loss of rock. The right side of the spillway lip is showing signs of erosion and needs to be monitored. The reservmr watergate platform and walkway surface is bare and needs to be sealed. No seepage has been detected around the dam. The water seeps from the hillside, appearing in the road at the rock notch (near station 06+00) and near the bottom of the hill (near station 44+90). Seepage appears normal and has not increased compared to past observations. The sandbags were removed. Sandbags should be used to increase storage during the cannery operation. They should be placed in a pyramid fashion and not increase the water height above the concrete sidewall on the spillway. No water must flow under the gabion baskets. The penstock was drained on 4/22/03. The bypass valves was opened 4 threads on valve stem, (about 2 inches of stem). It took about 6 hours to drain penstock. This should be the maximum normal rate to prevent a penstock collapse. The penstock was filled on 4/23/03. The penstock gate valve at reservoir was opened 6 threads on valve stem, (about 3 inches). It took about 4 hours to fill the penstock. This should be the maximum normal rate to fill to allow air to escape without building pressure in the penstock. Positive air pressure was noted at the air release standpipe. \Vaterway The Bypass and Penstock valve guides were straight and no icing damage noted. The intake box sealer was holding up well, except for an 8 inch wide band at the water line, which had been removed by ice and water surface fluctuation. There are two breaks in the head level gage wiring to dam. Air valves were replaced at the two lower locations on the penstock. The power plant tailrace structure, left side, lower comer at the bend is showing signs of erosion. The tailrace concrete structure is showing severe signs of deterioration near the top of wall on both sides of the tailrace. Epoxy grouting is recommended to stop the eros10n. Powerhouse Equipment The control batteries were replaced with new ones. The new pressure relief valve was installed. The unit was started at 2030 on 4/23/03. The unit tripped off line at 00:00:01 on 4/24/03. The software program was corrected the next morning and plant restarted. The plant was put back on line at 0830 on 4/24/03. The equipment nameplate data is: Generator KATO MFG. Model A246890000, 475KW @ .9 P.F., 480 Volt, 3 Phase, 900 RPM, Cat: 8P6-1500, Serial No. 96238, Type 24689 Main Power Circuit Breaker Westinghouse Type SPB65, 800 A., Ser. No. 21E3033 1A18506G68, 600V, 3 pole Governor Circuit Breaker Westinghouse Series C, 90 amp visabreaker, 600V, 3 pole, .:.cat. No. FOB3090 S, style 8985A63G54 Turbine CANYON INDUSTRY, Custom Double Nozzle, 22"p.d., Maximum Flow: 11.00 CFS @ 475 KW, Minimum Flow 1.00 CFS @ 47 KW, Average Flow 3.20 CFS @ 150 KW, 316 SS Pelton Wheel has 2 nozzles and 2 deflectors, 20 cups, Penstock Pressure 290 PSI. Controller THOMPSON & HOWE ENERGY SYSTEMS INC. Prod. No. SG450KW480V, Ser. No. 91SG45, 60HZ, 800 A., Load Tank: Solid state 120 KW resistor load controller Ser. No. 91M56 Computer Chip: S27C648-2317N02-9135RG Hydro Transformer Jerry's Electric Type 1.0388-22, SOOKV A, 12.4717.2KV 480V,Transformer Grounded Star-Delta, 1.0% Z, 65 degree Rise Cannery Transformer ABB Style V73E5642RB, 500 KVA, 12.4717.2 KV-480/277 V, 1.44% Z, 95 KV BIL, Grd. Star-Star, 191 gal, 4890 lbs, Ser. No. 911924008, July 1991 Cannery Circuit Breaker SquareD, Type SEF, Cat. No. SEF36800LSGEVIA4, 600V, 400A Diesel Powerplant Circuit Breaker SquareD, Type SEF; Cat. No. SEF36800LSGEVIA4, 600V, 400A Diesel Powerplant Switch Hl S&C Elec. Co., Pad Mount, Mod. 53152R1-E3F2GlG2HJ, Ser. No. 903274, June 1990,ManualPMS-9 Relief Valve Cla-VAL Co., 6", 300 mwp psi, #82809-0lD Turbine Inspection The turbine runner was inspected. The repairs made in Oct 2001 were holding up very well. No cracks or cavitation were found. Minor surface defects were noted on buckets 13, 15, and 16. #13. Scoring on back side ofbucket described as Yz" long x 1116" wide x 1/32" deep. #15. A gouge on back side 3" long x 1/16" wide x 1116" deep. # 16. A minor flaw on back side of bucket with shadow frosting cavitation on front in the cup. There is also a surface defect on the turbine hub about 3/16" deep. Generator The generator was lubricated and inspected. The generator and turbine were running without vibration after the alignment in Oct. 2001. The hydro transformer containment area should be resurfaced to prevent further erosion. The cannery transformer containment needs to be rebuilt and the containment wall put back into place. The moss vegetation should be removed from the containment areas. Controls Trevor Kudrna, EPS installed a new software program to update the hydro unit control operations. Buildings/Facilities The powerhouse was clean. The Powerplant building facia needs to be repaired, scraped and repainted. Roads and Bridges The road to the project dam needs to be maintained. The water from the slot was running down the road. It should be diverted by a water bar, near the slot, to prevent it from running down the road and softening the ground above the penstock, which is in the road. The slot is filling with the debris and material sluffing off the banks. Equipment The project Honda 4X4 4 wheeler was out of service. 3.0 OPERATIONS AND MAINTENANCE Safety The tagging procedures for equipment safe clearances are being followed and training conducted again for the new operators. Water Availability It appears that the water flows are good. Annual flow data is not maintained. The cannery is to operate this year. General Maintenance and Housekeeping The overall maintenance and housekeeping was good. A project equipment, spare parts, and tool inventory is recommended to be performed. Security The project entry gate and fence needs to be straightened and repaired. Records A new daily hydro plant record was recommended to be used. 4.0 RECOMMENDATIONS 1. Position the spillway sandbags to capture the maximum water for generation. 2. Perform a project inventory of equipment, tools, and spare parts. 3. Blade the project dam road and provide a ditch so the water can drain to side of road. 4. The reservoir watergate platform and walkway surface is bare and needs to be sealed. 5. The head level gage wiring needs to be replaced. 6. Powerplant building fascia needs to be scraped and repainted. 7. The project entry gate and fence needs to be straightened and repaired. 8. Repair the tailrace concrete deterioration. 9. Insulate the air valve boxes to prevent the air valves from freezing. 10. Install permanent air screens on air vent stand pipe. 1 L Paint the intake box at the next draining of the reservoir. 12. Clean and Flush the reservoir and sump area as soon as possible and at the very latest by Sept. 30, 2003. 13. Remove moss from transformer containment area and the dam spillway. 14. Complete installation of remote dial-up software upgrades by repairing phone lines. 15. Use new electric meter panels to more accurately monitor and record usage data. 16. Continue with nom1al maintenance and daily inspections and complete daily and monthly inspection reports as noted in the Larsen Bay Hydro Operating and Maintenance Procedures provided. 17. Remove alders that encroach on the reservoir. A6out FERC News Congress Projects r·Jear You About FERC Get Involved Citizen Guide LNG Overview 'All of FERC • ii1 Ill•••• elibrary j Students Corner j Sitemap I Home Doc~f!lents & Industries Filings Legal Resources Market Oversight Enforcement For Contact Citizens Careers Us Help for Citizens » Citizen's Guides » Hydropower Licensing Hydropower Licensing Under the Federal Power Act, the Federal Energy Regulatory Commission has the exclusive authority to license nonfederal hydropower projects on navigable waterways and federal lands. Building and operating hydropower projects can affect the natural environment and result in changes to land use, which may be of concern to local citizens and non-governmental organizations. We want you to know: • How the Commission's hydropower procedures work; • What rights you have; • How you can participate in the licensing process; and • What environmental issues and safety concerns may be involved. Background The Commission issues initial (original) hydropower licenses for periods between 30 to 50 years. When a license expires, the Commission can: • Issue a new license (relicense); • The federal government may take over the project; or • The project may be decommissioned. Many hydropower licensing concerns involve natural resource issues. For example, hydropower project operations generally alter natural river flows, which may affect fisheries and recreational activities. Project construction or expansion may also affect wildlife habitat, wetlands or cultural resources. Land owners and communities Contact Information Office of Energy Projects Telephone: 202-502-8700 Toll-free: 1- 800-847-8885 Enforcement Hotline Telephone: 202-502-8390 Toll-free: 1- 888-889-8030 Dam Safety Problems Telephone: 202-502-6734 Hydropower Compliance Issues Telephone: 202-502-6377 file://G: \FERC%20Citizen's%20Gu ides%20-%20Hydropower%20Licensing. htm 10/7/2008 =ERC: Citizen's Guides-Hydropower Licensing downstream of a project also want to be assured that the project dam is safe. The Commission's staff prepares an environmental analysis of every hydropower proposal. This is done both for new projects (original license) and for existing projects (relicense). Before the environmental analysis is prepared, Commission staff may hold public scoping meetings in the local vicinity of the project, and may conduct a site visit to the project. The purpose of scoping is to identify issues relating to the construction or continued operation of a project. Citizens and interested groups have a number of opportunities to participate in the licensing process, in order to identify potential issues and to share their views on how to address the effects of the project on the natural and human environment. This includes a pre-filing meeting required to be held before the application is filed with the Commission! during the scoping process, and when the draft environmental report is issued. If you own land that may be affected by a proposed new projectr or expansion of an existing project, you will have an opportunity to negotiate directly with the company regarding compensation. If the Commission approves the license application and you fail to reach agreement with the companyr access to and compensation for use of your land will be set by a court. The Commission's process for assessing applications for hydropower projects is open and publicr and designed to keep all interested parties informed. Updated: May 21, 2008 Page 2 ot 2 Privacy Policy 1 Ethics 1 Accessibility I No Fear Act I Disclaimers I Webmaster I Continuity of Operations Plan (COOP) I USA.gov I Adobe Reader m file://G:\FERC%20Citizen's%20Guides%20-%20Hydropower%20Licensing.htm 10/7/2008 Joint Ventures Building Seismic Safety U S. Department ofthe Interior Mission Statement "To ensure Reclamation dams do not present unacceptable risk to people, property, and the environment" Dam Safety Overview Reclamation's Dam Safety Program was officially implemented in 1978 with passage of the Reclamation Safety ofDams Act, Public Law 95-578. This act was amended in 1984 under Public Lm.v 98-404. Program Development and administration of safety of dams activities is the responsibility of Reclamation's Dam Safety Office located in Denver, Colorado. Dams must be operated and maintained in a safe manner, ensured through inspections for safety deficiencies, analyses utilizing current technologies and designs, and corrective actions if needed based on current engineering practices. In addition, future evaluations should include assessments of benefits foregone with the loss of a dam. For example, a failed dam can no longer provide needed fish and wildlife benefits. The primary emphasis of the Safety Evaluation ofExisting Dams (SEED) program is to perform site evaluations and to identify potential safety deficiencies on Reclamation and other Interior bureaus' dams. The· basic objective is to quickly identify dams which pose an increased threat to the public, and to quickly complete the related analyses in order to expedite corrective action decisions and safeguard the public and associated resources. The Safety of Dams (SOD) program focuses on evaluating and implementing actions to resolve safety concerns at Reclamation dams. Under this program, Reclamation will complete studies and identify and accomplish needed corrrective action on Reclamation dams. The selected course of action relies on assessments of risks and liabilities with environmental and public involvement input to the decisionmaking process. Last Updated: For site maintenance contact: Webmaster Privacy Policv I Disclaimer \ AccessibilitY I FOIA \ Quality of lnfonnation I F AQ I Notices DOl_\ Recreation.goy \ USA.gov Go to Table of Contents ---·~·-··-- ;;~(jii ~>:., Guidelines for Cooperation · il1jll\with the vW Alaska Dam Safety Program """'""'~"'··~- 1- Prepared by Dam Safety and Construction Unit Water Resources Section Division of Mining, Land and Water Alaska Department of Natural Resources June 2005 CHAPTER 1. WELCOME TO THE ALASKA DAM SAFETY PROGRAM o Developing policies, plans, and procedures necessary for complying with the requirements of the applicable dam safety statutes and regulations o Sustaining the project by providing all funding necessary to design, construct, operate, maintain, repair, and, if necessary, remove the dam at the end of the life of the project o Hiring personnel qualified to manage and operate a dam in a safe manner Typical Dam Owners In Alaska Municipalities State and federal agencies Native corporations Private and public owned businesses and corporations · o Retaining qualified engineering consultants and contractors to complete any work beyond the expertise of the owner or the ovvner' s employees o Ensuring the quality and success of the overall project 1.3.3 Operator of o .. For purposes of these guidelines, the "operator" of a dam is considered to be that legal extension of the owner of the dam who is actually involved in the daily operation of the dam. As such, the operator of the dam is responsible for the following: o Executing those policies, plans, and procedures, developed by the owner, necessary for complying with the requirements of the applicable dam safety statutes and regulations o Developing and performing the requirements of the O&M program o Monitoring the performance of the dam under all conditions (including routine and extraordinary inspections), reading instrumentation, and analyzing and reporting of data o Developing and maintaining the EAP, activating the plan when necessary, executing the responsibilities of the operator outlined in the plan, and exercising and revising the plan on a regular basis to ensure that the plan is current o Maintaining all records associated with the dam, including design and construction records, routine inspection records, PSI reports, incident reports, and certificates of approval o Developing and implementing recurrent training programs to educate employees on their specific duties related to the dam 1.3.4 Qualified En•neer Typical Dam Operators in Alaska Public works departments Utilities Mines Fish hatcheries and processors tlecause a dam is a unique and complex engineered structure that has certain associated risks, an experienced engineer is required to assure that a dam is designed, built, and operated with appropriate concerns for safety. A "qualified engineer" is defined in the Alaska dam safety regulations under Title 11, Chapter 93, Section 193, of the Alaska Administrative Code (11 AAC GUIDEUNES FOR COOPERATION WITH THE ALASKA DAM SAFETY PROGRAM 1-4 REVISION 1 jUNE 30, 2005 of Contents REGUlATION OF ALASKA DAMS Section 93.173, Certificates of Approval-Outlines the circumstances under which the department may issue, deny, or revoke a certificate of approval, as well as conditions and admini'ltrative requirements for the various certificates of approval issued by the ADNR. Section 93.175, Records Lists the requirements for records to be kept by the owner of a dam. Section 93.177, Reporting of Dam Incidents-Requires the dam owner to report certain incidents involving the dam to the ADNR. Section 93.193, Qualified Engineers -Identifies the minimum qualifications of an engineer who can seal the following documents requiring ADNR approval: proposed hazard potential classifications, design engineering reports, design and construction drawings, construction specifications, consl:n.!ction completion reports, and other engineering documents. In addition, the qualifications of engineers who may be approved by the ADNR for conducting PSis are identified. Section 93.195, Inundation Maps and Inflow Design Flood Information-Lists requirements for the development of inundation maps and inflow design floods. Section 93.197, Operation and Maintenance Manuals Identifies the requirements for the contents of an operation and maintenance manual, which is required for all dams. Section 93.201, Definitions Provides definitions of select terminology. 2.3 Definition of a State Jurisdictional Datn To determine if a dam is under state jurisdiction, AS 46.17.900(3) defines a dam as an" artificial barrier and its appurtenant works, which may impound or divert water" and which meets at least one of the following three descriptions: o "(A) Has or will have an impounding capacity at maximum water storage elevation of 50 acre-feet and is at least 10 feet in height measured from the lowest point at either the upstream or downstream toe of the dam to the crest of the dam." A dam with a jurisdictional height (H) of 10 feet or taller and that stores 50 acre-feet or more of water meets this description, as illustrated in Figure 2-1. o "(B) Is at least 20 feet in height measured from the lowest point at either the upstream or dm.v.nstream toe of the dam to the crest of the dam." A dam that is 20 feet or more in height meets this description regardless of its storage capacity, as illustrated in Figure 2-2. o "(C) Poses a threat to lives and property as determined by the department after an inspection." In other words, a barrier with a Class I (high) or Class II (significant) hazard potential classification is considered a dam, even if it does not meet the geometric criteria of A or B, above. See Section 2.4 for guidance in determining the hazard potential cla'lsification. THE AlASKA DAM SAFETY PROGRAM REVISION 1 jUNE 30, 2005 CHAPTER 2. BASIS FOR REGULATION OF ALASKA DAMS the volume should be calculated at the elevation of the maximum stage during the flood. The height of the dam would still be measured to the crest of the dam to include freeboard. If a dam is to be used for storing substances other than clean water, such as sewage, sludge, or mine tailings, but which still have the ability to flow similarly to water under certain conditions, the principles outlined above still apply. If the failure of the dam could result in the release of substances that could create a significant danger or risk to public health, that dam will be considered at lP.ast a Oass II (significant) hazard dam. To reach agreement on which dams meet the statutory definition of a dam and, therefore, fall under the jurisdiction of the ADSP, Dam Safety developed the Ha7...ard Potential Classification and Jurisdictional Review Form presented in Appendix A. Additional information about the hazard potential classification is presented in the following section, and dam failure analysis is presented in Section 9.3. 2.4 Hazard Potential aassification The hazard potential classification is the main parameter for determining the level of attention that a dam requires throughout the life of the project, from conception to removal. The hazard potential classification represents the basis for the scope of the design and construction effort, and dictates the requirements for certain inspections and emergency planning. The ADSP uses three classifications for dams based on the potential impacts of failure or improper operation of adam: o Class I (high) CJ Class II (significant) o Class III (low) The hazard potential classifications are explained in detail in 11 AAC 93.157 and are summarized in Table 2-1. Dams are classified based on theoretical estimates of the potential impact to human life and property if the dam were to fail in a manner that is typical for the type of dam under review, or if improper operation of the dam could result in adverse impacts. The actual or perceived quality of design and construction and the condition of the dam are irrelevant for the classification, but may influence other requirements such as the frequency of monitoring, the scope of PSis, and the content of O&M manuals and EAPs. To determine the hazard potential classification consistently and equitably for projects, Dam Safety developed the Hazard Potential Classification and Jurisdictional Review Form in Appendix A, as previously mentioned. This form should be completed by a qualified engineer based on the existing or proposed configuration of the dam, and subm.itted to Dam Safety for review and concurrence. GUIDEUNES FOR COOPERATION WITH THE ALASKA DAM SAFETY PROGRAM 2·9 REVISION 1 jUNE 30, 2005 CHAPTER 2. BASIS FOR REGULATION OF ALASKA DAMS Table 2-1. Hazard Potential Classification Summary Hazard Class Effect on Human Life Effect on Property I (High) Probable loss of one or more lives Irrelevant for classification, but may include the same losses indicated in Class II or Ill II (Significant) No loss of life expected, although a significant danger to public health may exist Probable loss of or significant damage to homes, occupied structures, commercial or high-value property, major highways, primary roads, railroads, or public utilities, or other significant property losses or damage not limited to the owner of the barrier Probable loss of or significant damage to waters identified under 11 AAC 195.01 O(a) as important for spawning, rearing, or migration of anadromous fish Ill (Low) Insignificant danger to public health Limited impact to rural or undeveloped land, rural or secondary roads, and structures Loss or damage of property limited to the owner of the barrier The form presented in Appendix A is designed as a "tickler" to remind the engineer of important aspects that should be considered in the review. In addition, the form is designed to be progressive. Three levels of review are available: o Preliminary -An initial, conservative assignment based on a visual inspection of the dam, the reservoir, the downstream reach, and other limited, readily available information such as aerial photography and topographic maps o Qualitative -A limited engineering evaluation that may involve crude hydrological estimates, simplistic peak discharge calculations for a dam failure or mis-operation, open-channel flow calculations, elevation or cross-section surveys, and simplistic data used with conservative assumptions o Quantitative -A detailed dam failure analysis that includes failure mode evaluation, computerized dam-break and hydraulic- routing models, detailed hydrological estimates, and good-quality input data Potential Future Development and Hazard Potential Classification A hazard potential classification determines the standard for the design, construction, and operation of the dam during the life of the project. If additional downstream development is likely, the dam should be designed and constructed to standards for the higher classification, although the dam may be classified and managed for existing conditions until the future development occurs. The higher levels of analyses and detail carry more credibility in the assignment of the classification. For example, a preliminary assignment of a Class II (significant) hazard potential could be overruled if a qualitative or quantitative review demonstrates that .the potential for adverse impacts is actually low. In another example, if new development occurs below an existing Class III (low) hazard dam, a qualitative analysis may be used to upgrade the dam to a Class I (high) hazard, whereas a quantitative analysis may demonstrate that a Class II I 1 l GUIDELINES FOR COOPERATION WITH THE ALASKA DAM SAFETY PROGRAM 2-10 REVISION 1 jUNE 30, 2005 CHAPTER 2. BASIS FOR REGULATION OF ALASKA DAMS (significant) hazard is the appropriate classification. Additional information about dam failure analysis is presented in Section 9.3. The ADSP hazard potential classifications were modified in the current regulations to be consistent with guidance contained in the following source: o Federal Guidelines for Dam Safety: Hazard Potential Classification System for Dams, published by the Federal Emergency Management Agency (1998b) Admittedly, much of the terminology used in 11 AAC 93.157 is not specific; for example, "probable" is not currently defined. Dam Safety will consider arguments presented by dam owners for hazard potential classifications that are in dispute, including risk assessments that quantitatively assign probabilities to certain outcomes. Nevertheless, those arguments should be cooperatively developed, technically sound, and justifiable. Additional information about risk assessments is presented in Section 12.3. The following references may also be helpful in assigning the hazard potential classification: o Evaluation Procedures for Hydrologic Safety of Dams, published by the American Society of Civil Engineers (1988) o "Dam Break Inundation Analysis and Downstream Hazard Oassification," Technical Note 1, in Dam Safety Guidelines, published by the Washington State Department of Ecology (WSDOE) (1992) 2.5 Associated Pennits and Regulatory Agencies This publication provides guidance only for the permits and submittals associated with the ADSP. In addition to the design and construction submittals discussed in Chapter 5, only the following information is required by 11 AAC 93.171 before Dam Safety will issue a Certificate of Approval to Construct a Dam: o For dams and reservoirs to be located partially or completely on property not owned by the dam owner, the property owners must provide legal permission to construct the dam or reservoir. A copy of the land use permit must be provided to Dam Safety. o Proof of a water right or water right application, as required by AS 46.15. GUIDELINES FOR COOPERATION WITH THE ALASKA DAM SAFETY PROGRAM Coordination of Permits Dam Safety wm not typically withhold a certificate of approval pending coordination with or conditional to any other permits that may be required from local, state, or federal agencies. However, those other permits may be required before construction can actually occur. Dam Safety will work within the framework of the Alaska Department of Natural Resources Large Mines Project Team and the Alaska Coastal Management Program for associated projects that include dams. Coordination of permits for other projects is the responsibility of the applicant. jUNE 30, 2005 ITEM ALASKA DAM SAFETY PROGRAM VISUAL INSPECTION CHECKLIST CONCRETE DAMS YES NO CONCRETE DAMS 1. CREST a. Any settlement? b. Any misalignment? c. Any cracking? d. Any deterioration? e. Exposed reinforcement? d. Adequate freeboard? 2. UPSTREAM FACE a. Spalling? b. Cracking? C. Erosion? d. Deterioration? e. Exposed reinforcement? f. Displacement? g. Loss of joint fillers? h. Damage to membranes? i. Silt deposits upstream? 3. DOWNSTREAM FACE a. Spalling? b. Cracking? C. Erosion? d. Deterioration? e. Exposed reinforcement? f. Inspection gallery? g. Foundation drains? h. Foundation drains clear and flowing? i. Seepage from joints? j. Seepage from lift lines? 4. ABUTMENT & FOUNDATION CONTACTS a. Exposed bedrock? b. Erosion? C. Visible displacement? d. Seepage from contact? e. Boils or springs downstream? NIDID# ___ _ SHEET OF REMARKS TYPE OF DAM: TYPE: ITEM ALASKA DAM SAFETY PROGRAM VISUAL INSPECTION CHECKLIST INTAKES YES NO INTAKES 1. EQUIPMENT a. Trash racks b. Trash rake? c. Mechanical equipment operable? d. Intake gates? e. Are racks and gates operable? f. Are gate operators operable? 2. CONCRETE SURFACES a. Any cracking? b. Any deterioration? C. Erosion? d. Exposed reinforcement? e. Are joints displaced? f. Are joints leaking? 3. CONCRETE CONDUITS a. Any cracking? b. Any deterioration? c. Erosion? d. Exposed reinforcement? e. Are joints displaced? f. Are joints leaking? 4. METAL CONDUITS a. Is metal corroded? b. Is conduit damaged? c. Are joints displaced? d. Are joints leaking? 5. METAL APPURTENANCES a. Corrosion? b. Breakage? c. Secure anchorages? 6. PENSTOCKS a. Material deterioration? b. Joints leaking? C. Supports adequate? d. Anchor blocks stable? NIDID# ___ _ SHEET OF REMARKS TYPE MATERIAL: ITEM ALASKA DAM SAFETY PROGRAM VISUAL INSPECTION CHECKLIST LOW LEVEL OUTLET YES NO LOW LEVEL OUTLET 1. GATES a. Mechanical equipment operable? b. Are gates remotely operated? C. Are gates maintained? 2. CONCRETE CONDUITS a. Any cracking? b. Any deterioration? c. Erosion? d. Exposed reinforcement? e. Are joints displayed? f. Are joints leaking? 3. METAL CONDUITS a. Is metal corroded? b. Is conduit cracked? c. Are joints displaced? d. Are joints leaking? 4. ENERGY DISSIPATERS a. Any deterioration? b. Exposed reinforcement? 5. METAL APPURTENANCES a. Corrosion? b. Breakage? c. Secure anchorages? NIDID# ___ _ SHEET OF REMARKS TYPE ITEM ALASKA DAM SAFETY PROGRAM VISUAL INSPECTION CHECKLIST SPILLWAYS YES NO SPILLWAYS 1. CREST a. Any settlement? b. Any misalignment? c. Any cracking? d. Any deterioration? e: Exposed reinforcement? f. Erosion? g. Silt deposits upstream? 2. CONTROL STRUCTURES a. Mechanical equipment operable? b. Are gates maintained? C. Will flashboards trip automatically? d. Are stanchions trippable? e. Are gates remotely controlled? 3. CHUTE a. Any cracking? b. Any deterioration? c. Erosion? d. Seepage at lines or joints? 4. ENERGY DISSIPATERS a. Any deterioration? b. Erosion? c. Exposed reinforcement? 5. METAL APPURTENANCES a. Corrosion? b. Breakage? c. Secure anchorages? 6. EMERGENCY SPILLWAY a. Adequate grass cover? b. Clear approach channel? c. Erodible downstream channel? d. Erodible fuse plug? e. Stable side slopes? f. Beaver dams present? NIDID# ___ _ SHEET OF REMARKS TYPE(S): TYPE{S): ITEM ALASKA DAM SAFETY PROGRAM VISUAL INSPECTION CHECKLIST TIMBER DAMS YES NO TIMBER DAMS 1. CREST a. Any settlement? b. Any misalignment? C. Adequate freeboard? d. Deck timbers sound? 2. ABUTMENT AND FOUNDATION CONTACTS a. Any erosion? b. Seepage present? C. Boils or springs downstream? d. Exposed bedrock? e. Is bedrock deteriorating? f. Visible displacements? 3. STRUCTURAL AND CRIB TIMBERS a. Any deterioration? b. Are ends broomed or checked? C. Are timbers preservation treated? d. Are timbers pinned or batted? 4. CRIBS a. Are cribs filled with rock fill? b. Is rock fill sound rock? NIDID# ___ _ SHEET OF REMARKS TYPE: TYPE: ITEM ALASKA DAM SAFETY PROGRAM VISUAL INSPECTION CHECKLIST EMBANKMENT DAMS YES NO EMBANKMENT DAMS 1. CREST a. Any settlement? b. Any misalignment? c. Any cracking? d. Adequate freeboard? 2. UPSTREAM SLOPE a. Adequate slope protection? b. Any erosion or beaching? c. Trees or brush growing on slope? d. Deteriorating slope protection? e. Visual settlement? f. Any sinkholes? 3. DOWNSTREAM SLOPE a. Adequate slope protection? b. Any erosion? c. Trees or brush growing on slope? d. Animal burrows? e. Sinkholes? f. Visual settlement? g. Surface seepage? h. Toe drains dry? i. Relief wells flowing? j. Slides or slumps? 4. ABUTMENT CONTACTS a. Any erosion? b. Seepage present? c. Boils or springs downstream? 5. FOUNDATION a. If dam is founded on permafrost (1) Is fill frozen? (2) Are internal temperatures monitored? b. If dam is founded on bedrock (1) Is bedrock adversely bedded? (2) Does rock contain gypsum? (3) Weak strength beds? c. If dam founded on overburden (1) Pipeable? (2) Compressive? (3) Low shear strength? NIDID# ___ _ SHEET OF REMARKS TYPE: TYPE: TYPE: TYPE: TYPE: ALASKA DAM SAFETY PROGRAM VISUAL INSPECTION CHECKLIST SAFETY ITEM YES NO SAFETY 1. ACCESS a. Road access? b. Trail access? C. Boat access? d. Air access? e. Access safe? f. Security gates and fences? g. Restricted access signs? 2. PERSONNEL SAFETY a. Safe access to maintenance and operation areas? b. Necessary handrails and ladders available? C. All ladders and handrails in safe condition? d. Life rings or poles available? e. Limited access and warning signs in place? f. Safe walking surfaces? 3. DAM EMERGENCY WARNING DEVICES a. Emergency Action Plan required? b. Emergency waming devices required by EAP? C. Emergency waming devices available? d. Emergency waming devices operable? e. Emergency waming devices tested? f. Emergency warning devices tested by owner? g. Emergency procedures available at dam? h. Dam operating staff familiar with EAP? 4. OPERATION AND MAINTENANCE MANUAL a. 0 & M Manual reviewed? b. 0 & M Manual current? c. Contains routine inspection schedule? C. Contains routine inspection checklist? NIDID# ___ _ SHEET OF REMARKS TYPE: TYPE(S): WHEN: DATE: NAME OF DAM: ALASKA DAM SAFETY PROGRAM VISUAL INSPECTION CHECKLIST GENERAL INFORMATION POOL ELEVATION: NATIONAL INVENTORY OF DAMS 10#: TAILWATER ELEVATION: OWNER: CURRENT WEATHER: HAZARD POTENTIAL CLASSIFICATION: PREVIOUS WEATHER: SIZE CLASSIFICATION: INSPECTED BY: PURPOSE OF DAM: INSPECTION FIRM: 0 & M MANUAL REVIEWED: DATE OF INSPECTION: EMERGENCY ACTION PLAN REVIEWED: ITEM YES NO RESERVOIR 1. Any upstream development? 2. Any upstream impoundments? 3. Shoreline slide potential? 4. Significant sedimentation? 5. Any trash boom? 6. Any ice boom? 7. Operating procedure changes? DOWNSTREAM CHANNEL 1. Channel a. Eroding or Backcutting b. Sloughing? c. Obstructions? 2. Downstream Floodplain a. Occupied housing? b. Roads or bridges? c. Businesses, mining, utilities? d. Recreation Area? e. Rural land? f. New development? EMERGENCY ACTION PLAN 1. Class I or Class II Dam? 2. Emergency Action Plan Available? 3. Emergency Action Plan current? 4. Recent emergency action plan exercise? DATE: INSTRUMENTATION 1. Are there a. Piezometers? b. Weirs? c. Observation wells? d. Settlement Monuments? e. Horizontal Alignment Monuments? f. Thermistors? 2. Are readings a. Available? b. Plotted? c. Taken periodically? NID •l.JTT:.__ __ _ SHEET OF REMARKS 1. Introduction 1.1 Maintenance 1.1.1 General This document is intended to establish standard practice as well as to give general advice and guidance in the maintenance of electrical equipment owned and operated by the Bureau of Reclamation. Specific technical details of maintenance are included in other documents which are referenced in this document. Power Equipme~t Bulletins are available on}yto~~lama~on personnel and may be found onthe intranet at http://intranet.ushi:gov/-hydrores/. Maintenance recommendations are based on industry standards and experience in Reclamation facilities. However, equipment and situations vary greatly, and sound engineering and management judgment must be exercised when applying these recommendations. Other sources of information must be consulted (e.g., manufacturer's recommendations, unusual operating conditions, personal experience with the equipment, etc.) in conjunction with these maintenance recommendations. 1.1.2 Preventive Maintenance Preventive maintenance (PM) is the practice of maintaining equipment on a regular schedule, based on elapsed time, run-time meter readings, or number of operations. The intent of PM is to "prevent" maintenance problems or failures before they take place by following routine and comprehensive maintenance procedures. The goal is to achieve fewer, shorter, and more predictable outages. Some advantages of preventive maintenance are: • It is predictable, making budgeting, planning, and resource leveling possible. • When properly practiced, it generally prevents most major problems, thus reducing forced outages, "reactive maintenance," and maintenance cosL<; in genera1.1 • It gives managers a level of assurance that equipment is being maintained. • It is easily understood and justified. Preventive maintenance does have some drawbacks: • • • It is time consuming and resource intensive . It does not consider actual equipment condition when scheduling or performing the maintenance. It can cause problems in equipment in addition to solving them (e.g., damaging seals, stripping threads). 1 World Class Maintenance Management, Terry Wireman, Industrial Press Inc., 1990, pg. 7, 73. Despite these drawbacks, PM generally has proven to be reliable in the past and is still the core of most maintenance programs. Traditionally, preventive maintenance has been the standard maintenance practice in Reclamation. The maintenance recommendations in this document are based on a PM philosophy and should be considered as "baseline" practices to be used when managing a maintenance program. However, care should be taken in applying PM recommendations. Wholesale implementatio~ of PM recommendations without considering equipment criticality or equ~ptmmtconditio.h may result in a workload that is too large to achieve. This cl:luld result in important equipment not receiving needed maintenance, which defeats the purpose of PM. To mitigate this problem, maintenance managers may choose to apply a consciously chosen, effectively implemented, and properly documented reliability-centered maintenance (RCM) program or augment PM with condition- based maintenance (CBM) practices. Whether utilizing a PM, RCM, or CBM, ()r a combination of these, the primary focus of the in-house maintenance staff should be scheduled maintenance? This will reduce reactive (emergency and corrective) maintenance. Scheduled maintenance should have a higher priority i:hall special projects. SdiedUied maintenance should be the number one priority. 1 .. 1.3 Reliability Centered Maintenance Reliability-centered maintenance programs are gaining in popularity and have been piloted in a few Reclamation power facilities with good results. The goal of these programs is to provide the appropriate amount of maintenance at the right time to prevent forced outages while at the same time eliminating unnecessary maintenance. Implemented properly, RCM can eliminate some of the drawbacks of preventive maintenance and may result in a more streamlined, efficient maintenance program. RCM seeins very attractive in times of diminishing funding, scarcity of skilled maintenance staff, and the pressure to "'stay online" due to electric utility industry deregulation. Some features of RCM are: • Labor intensive and time consuming to· set up initiaJ1y; • May require additional monitoring of quantities like temperature and vibration to be effective. This may mean new monitoring equipment with its own PM or more human monitoring with multiple inspections. • May result in q, "run-to-failure" or deferred maintenance philosophy for some equipment with its own PM, which may cause concern for some staff and managers. 2 World Class Maintenance Management, Terry Wireman, Industrial Press Inc., 1990, pg. 32. 2 • May require initial and later revisions to the maintenance schedule in a "trial- and-error" fashion depending on the success of the initial maintenance schedule and equipment condition. • Should result in a more manageable maintenance workload focused on the most important equipment. RCM is not an excuse to move to a "breakdown maintenance" philosophy or to eliminate critical preventive maintenance in the name of reducing maintenance staff/funding. However, to mitigate problems associated with a PM program, maintenance managers may choose to apply a consciously chosen, effectively implemented, and properly documented RCM program. For RCM to be a viable program at Reclamation facilities, it must: • Be chosen as the local maintenance philosophy by management. • Be implemented according to generally accepted RCM practices. • Be documented so that maintenance decisions are defensible. 1.1.4 Condition-Based Maintenance This program relies on knowing the condition of individual pieces of equipment Some features of CBM include: • Monitoring equipment parameters such as temperatures, pressures, vibrations, leakage current, dissolved gas analysis, etc. • Testing on a periodic basis and/or when problems are suspected such as Doble testing, vibration testing, and infrared scanning. • Careful monitoring of operator-gathered data. • Results in knowledgeable maintenance decisions which would reduce overall costs by focusing only on equipment that really needs attention. Drawbacks to CBM include it being very difficult and expensive to monitor some quantities. It requires knowledgeable and consistent analysis to be effective, and condition monitoring equipment and systems themselves require maintenance. Because of these drawbacks, it is nearly impossible to have an entirely condition- based maintenance program. 1.1.5 Combination of Condition-Based and Preventive Maintenance A combination of condition-based maintenance and preventive maintenance is perhaps the most practical approach. Monitoring, testing, using historical data, and preventive maintenance schedules may provide the best information on when equipment should be maintained .. By keeping accurate records of the "as found" condition of equipment when it is. tofl1down for maintenance. one can. d~termine what maintenance was really necessary ... In this manner, maintenance sched:tiies can be lengthened or perhaps shortened, based on experience and monitoring. 3 - be scheduled, staffed, and budgeted. They may be scheduled on a time, meter, or number of operations basis but may be planned to coincide with scheduled equipment outages. Since these activities are predictable, some offices consider them "routine maintenance" or "preventive maintenance." Some examples are Doble testing, meggering, relay testing, circuit breaker trip testing, alternating current (AC) high-potential (Hipot) tests, high voltage direct current (HVDC) ramp tests, battery load,tests. • Diagnostic Testing -Activities that involve use of test equipment to assess condition of equipment after unusual events such as faults, fires, or equipment failure/repair/replacement or when equipment deterioration is suspected. These activities are not predictable and cannot be scheduled because they are required after a forced outage. Each office must budget contingency funds for these events. Some examples are Doble testing, AC Hipot tests, HVDC ramp tests, partial discharge measurement, wedge tightness, core magnetization tests, pole drop tests, turns ratio, and core ground tests. This FIST volume addresses scheduling of maintenance activities in the first two categories. It does not address followup work generated by routine maintenance or maintenance testing, nor does it address diagnostic testing (with a few exceptions). Also, maintenance staff may be used for other activities such as improvements and construction, but this guide does not address these activities. PEB No. 29, Electrical Testing Synopses, addresses standard tests for electrical equipment in Reclamation powerplants. 1.3.2 Infrared Scanning Annual infrared scans of electrical equipment are required by NFPA 70B, 18-17.5. Throughout this FIST volume, infrared (IR) scanning is recommended as a regular maintenance procedure. Infrared scanning and analysis have become an essential diagnostic tool throughout all industries and have been used in Reclamation to detect many serious conditions requiring immediate corrective action. Several forced outages already have been avoided. Infrared scanning is non-intrusive and is accomplished while equipment is in service. It can be used not only for electrical equipment but also to detect mechanical and structural problems. Therefore, infrared scanning is HIGHLY recommended as a regularly scheduled maintenance procedure. Effective infrared scanning and analysis require the following: • The scanning equipment (IR camera and accessories) must be high quality and correctly maintained and calibrated. • The IR camera operator must be trained to use the equipment and deal with complicating issues such as differing emissivities of surfaces and reflectivity. Certified Levell Thermographer (e.g., Academy ofiR Thermography) credentials, or higher, are recommended. • TheIR system operator must be able to analyze results using state-of-the-art software critical to successful interpretation of problems. 6 SOURCES Alaska Energy Authority (formerly Alaska Power Authority) Alaska vocational Technical center American Governor co. City of Larson Bay, Alaska cogeneration Technologies state of Alaska, DNR, Dam safety and construction unit western Area Power Administration wikipedia, the free encyclopedia wisconsin valley Improvement co. u.s. Bureau of Reclamation