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HomeMy WebLinkAboutUpgrade Ft. Yukon's Electrical Distribution System, Final Report 1994UPGRADE FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM FINAL REPORT Prepared for: Mr. David Thomas, Manager Gwitchyaa Zhee Utility Company Ft. Yukon, Alaska Prepared by: FPE Roen Civil Electrical Environmental Mechanical Survey EN-G f NEE R S 560 E. 34th Ave., Suite 300, Anchorage, AK 99503 Contact: James R. Pressley, P.E. Voice: (907) 561-1666 FAX: (907) 561-7028 December, 1994 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. ee A. EXECUTIVE SUMMARY The Gwitchyaa Zhee Utility Company commissioned this study to obtain estimated costs to upgrade its electrical service system. The existing system is of a less-than-modern configuration (2400 Volts, 3 phase, 3 wire "Delta"). Its evolution and extension have resulted in complaints from users about its ability to provide reliable and stable power. As the types and numbers of appliances and equipment users connect to the system become more numerous and sophisticated, the more reliability and stability will become the object of concern and complaint. This report presents an overview of the existing system, examines the impacts of upgrading to the next higher typical distribution system configuration and describes some areas in which improvements could be made. Finally, it assembles estimated costs for upgrading the system, recommends the upgrades be implemented and suggests a phasing arrangement that will result in the renovation of the existing system into an efficient, well managed and modern electrical service system that will meet Ft. Yukon’s power needs and requirements well into the foreseeable future. To combat the complaints about low voltage and fluctuations in the power delivery system, the voltage and configuration should be increased to 2400/4160 Volts, 3 phase, 4 wire grounded "Wye". The costs of upgrading the outside plant and making the changes in the existing system to accomplish that upgrade are roughly estimated at $375,000 in 1994 dollars. To modernize the system and make the process of delivering power more efficient and cost-effective, other revisions are suggested. To renovate the existing substation (a seriously weak link in the distribution system), provide the coordination and selectivity the system must have to be reliable, and bring the plant and its fuel system into compliance with current environmental and safety regulations, codes and standards, costs an estimated $1,335,000, again in 1994 dollars. This sum provides a new power plant, new fuel storage and distribution and new operations information and studies. See the Conclusions section for suggested phasing of costs to implement all the recommended improvements. Should all funding be available at a single time, the total costs to upgrade the GZU system and its facilities would be about $1,750,000. Page 1 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. ——$——————— eee ee B. PURPOSE Ft. Yukon’s existing electrical distribution utility system has reached the limits of its abilities to properly provide reliable and stable electrical service to its customers. The population continues to geographically expand into areas further and further from the power plant. The relatively low voltage used for distribution is insufficient to avoid voltage drop problems at the ends of the longer lines. The problems at the ends of the longer lines create transient voltages in other portions of the system leading to general dissatisfaction with the quality of service the utility provides. This study investigates the existing system and ways it might be improved. Specific emphasis is placed on upgrading the entire system to 4160/2400 volts, three phase, 4 wire "Y" configuration from its existing configuration of 2400 volts, 3 phase, 3 wire "delta". The proposed new system is the next higher voltage standard system configuration that will permit the continued use of the majority of existing installations and equipment to serve loads without completely or substantially replacing existing transformers, switches and other equipment. Other possible solutions to persistent undervoltage problems include relocating the power plant, providing a separate and additional power plant to work in conjunction with the existing plant and skipping this intermediate upgrade and going a step further to a 7200/4160 volt, 3 phase, 4 wire "Y" system configuration. The ultimate purpose for this study is to provide estimated costs for Ft. Yukon to upgrade its system in order for the regional economy to continue its growth and expansion without the restraints an insufficient electrical energy supply could impose. Cc. METHODOLOGY The techniques used to develop and prepare this study are rather basic. First, a brief telephone interview with Mr. David Thomas, Manager of the utility system was conducted to get a short glimpse into the history and recent performance of the electrical distribution system. A literary research effort was undertaken to document written material available describing the electrical distribution system, the character of the region and the population trends in the area. Page 2 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. A brief field investigation was made to observe the condition of the system and its components. On-site field interviews with Mr. Thomas and others were conducted to determine reliability, stability and problems with the system in the recent past. An abbreviated document search was undertaken in the local offices of the City and its administrative facilities to find all available information. The basis for this study is fairly broad-based and general. The objective is not to define prescriptive designs, but to provide estimated costs to upgrade the existing system. To define the existing system without a detailed recording of poles, hardware and equipment, a different approach was selected. The existing system was reviewed and generally reproduced on a City map for the purposes of further investigation. Using the total length of installed electrical distribution lines and configurations, some reasonable assumptions were made and approximate numbers of poles and reasonable complements of hardware and equipment were established to permit developing costs of alternatives. Once reasonable quantities were established, costs were assigned. Summaries of the results of those efforts can be found in the Executive Summary above and in the Assessment and Evaluation section below. D. ASSESSMENT AND EVALUATION ASSESSMENT The interviews, field investigations, research and approximations of service and equipment resulted in the following summary description. DESCRIPTION REMARKS Operating Configuration 2400 V.-3 ¢, 3 W. "Delta" Number of Connected Services 380 (Estimated) Number of Transformers 104 (Estimated) Length of Distribution System 7 Miles (Estimated) Length of 1 @ Distribution 3.5 Miles (Estimated) Length of 3 @ Distribution 3.5 Miles (Estimated) Length of Wire Installed 17 Miles (Estimated) Number of Utility Poles 300 Typical Crossarm Length 6 Feet, Wooden w/ Wood Braces Typical Pole 35 Ft., Class 5, Butt @ 6-7 Ft. Number of Substations 1 @ 750 KVA Typical Wire Size #4 ACSR Swan 8 Page 3 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. a ea ee Typical Pin Insulator ANSI 55-4, 65 KV Dry, 35 KV Wet Typical Suspension Insulator ANSI 52-9, 65 KV Dry, 35 KV Wet Total Prime Generation 1625 KVA Total Standby Generation 285 KVA Historical Peak Demand 530 KW There are several reasons why estimates were made to establish parameters for some of the data indicated in the summary. There are no figures that accurately record numbers of poles, numbers of transformers, span lengths or other material information. The precise calculation of costs associated with the alternatives must necessarily suffer, since only approximations can be made. The problems associated with the system were documented by interviews with the plant supervisor. The complaint most often mentioned was low voltage at the portions of the system further away from the power plant and its substation transformer. There were some allegations low voltage was responsible for the loss of an x-ray machine at the clinic. These allegations seem to be fueling opinions that GZU’s system is in some way causing other appliances and equipment to experience problems or fail altogether. EVALUATION There are several areas where improvements will make the GZU system more reliable, safe, stable and durable. The power plant and its surroundings should be investigated and a program developed to abate several of the hazards and problems which could lead to catastrophic interruption of power for long periods of time. Examples of the type of hazards which could result in partial or total destruction of the power plant and its appurtenances are 7 The power plant floor, the soils under and around the power plant and most of the plant’s surfaces are partially or completely saturated with diesel oil and other petroleum products. The smallest of fires could result in a complete burn-down. * The structure immediately outside the power plant which supports and encloses the conductors, connectors and equipment that constitute the only substation in the system, is fabricated of wood. This "tower" was built long ago. The creosoted timber has absorbed a lot of diesel fumes in its days of service and a small fire here or a lightning strike could create a long-term interruption of service throughout Ft. Yukon. Page 4 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. The bulk fuel storage tank outside the power plant does not meet EPA requirements and is not well protected from heavy equipment operating in the area of the power plant. A major disruption of fuel storage and delivery systems could start the fire that destroys the entire power plant and its surroundings. The most critical elements of the electrical utility system (power plant, substation and much of the distribution system) lie dangerously close to the flood plain near the river. The survival of the electrical utility would be greatly improved during potential catastrophic flooding if the entire plant and its appurtenances were relocated to higher ground and, hopefully, nearer the center of load the system is experiencing. Other serious issues exist. This report is not intended to address such problems and those other issues are not logged here. The fundamental problems with the GZU system are those typically found in an area of long-term settlement and expansion. The system has been in place so long it has evolved without planning or thought as to how changes would affect the entire system and its ability to provide stable quality electric! service. The low-voltage problems are the direct results of 2 things. The size of wire introduces more resistance than a larger wire would, and the voltage is too low for the wire lengths from the power plant to the loads at the end of the longer distribution lines. The load on 2 phases of the system far exceeds the load on the 3rd phase. This condition is known as "unbalanced". The difference in sizes of loads on each phase causes problems with generators, the substation transformer and all loads connected to the lightly loaded 3rd phase The system is arranged so loss of a simple component anywhere within it will cause everyone downstream from the failure to be without power for as long as is necessary to bring that portion of ths system back online. The "sag" of wire between poles in some sections of the system result in wires being slapped together in high winds. This contact causes loss of power, since it blows the primary fuses back at the substation. It has occurred so often, the fuses on the 2 phases which come in contact during windy conditions are "protected" by fuses with trip ratings 30% higher (65 amps.) than the remaining phase and its fuse(50 amps.). Page 5 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. There are few records documenting the problems, the repairs, the reliability, the stability and the complaints regarding the system and its operation. Likewise, there are no records describing the installed plant materials and equipment. No one knows with any great feeling of accuracy the number of poles in the system, the number of miles of distribution line, the number of transformers or any other information about the assets of GZU. The most accurate information regarding the number of services, the locations of transformers, the geometrical arrangement of distribution lines and other items describing the system comes from the memory of Mr. David Thomas, Plant Manager. No load flow studies, fault analyses, coordination evaluations, selectivity comparisons or other calculations have ever been performed for the Ft. Yukon electrical distribution system. Page 6 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. E. RECOMMENDATIONS The concept of modernizing the GZU distribution system by increasing its primary voltage to 4160 Volts should be implemented as quickly as feasible. The existing pole line construction should be upgraded as required for utilizing the higher voltage and phase configuration. All new poles, crossarms, hardware and installations should be arranged and erected in accordance with the requirements for 7200 Volt systems. This approach will permit an upgrade to 7200 Volts from 4160 Volts sometime in the future for less costs than starting from scratch. In any event, any crossarms purchased after the time a commitment is made to upgrade the system should be 8’-0" long. It is also recommended that all future crossarm angle braces be steel instead of wood. The minimum wire size used in the new system should be #2 AWG. The wire should be ACSR for strength. It should be properly installed with the sag and tension set as recommended by the wire manufacturer based on the conditions at the time of installation. The existing pin and suspension insulators are satisfactory for the new 4160 V. system. The new system should utilize a grounded neutral distribution arrangement and a neutral should be carried throughout the system. Additionally, lightning arresters should be installed at all critical points within the system to help keep lightning from permanently damaging wire, poles and equipment. In areas where 2-2400 Volt phases without a neutral have been distributing power, the arrangement should be changed to operate these lines at 2400 Volts Line-to- Neutral and one of the wires should be selected as the neutral and solidly grounded. An alternative technique for distributing service in those areas would be to drive ground rods at about 30-50% of all poles and add a neutral on a side mounted spool insulator at approximately 30" down the pole from the crossarm. Areas with 3 phase wires on the crossarms, must have a solidly grounded neutral added to the configuration. This addition can be accomplished in one of three ways. A pole top pin can be added to carry one of the phase wires. One of the phase wires on the crossarm nearest the pole can be shifted to that location. The position vacated by the phase wire can then become the neutral wire position. A second way to accomplish adding the neutral is to provide the neutral run below the crossarm and connected to the pole with a side mounted spool insulator. Page 7 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. The third way to incorporate the neutral into the configuration is to rearrange the phases and their separations in order to put the 4 wires of the new system on the crossarm and have all of them mounted on pin insulators. This technique might require the crossarm be changed from 6’ to 8’ in length should the subsequent upgrade from 4160 Volts to 7200 Volts ever occur. To achieve the new 2400/4160 V.-3 ¢, 4 W. configuration, the substation transformer must be reconnected. It has the taps available for that reconnection and the changeover is fairly simple. However, it must be noted, the changeover cannot occur until all the system installations and equipment are properly configured and rated for their new system’s characteristics. It is recommended during the transition from one system to the other, the records documenting the final system and its arrangement be created to permit simple references be used to locate and identify portions of the system in the future. Numbering each pole, assigning sector and branch designations, providing identification tags and stencils on equipment and other reference designators would make future efforts such as this one more definitive, more easily performed (and, therefore less costly) and more easily interpreted. The “tower’ should be demolished and replaced with a properly arranged and protected substation. The substation should be enclosed within a perimeter fence with locking gate. the space inside the fence should be well graded and compacted fill with the major equipment items mounted on concrete pads. Sufficient clearances for safety and maintenance must be maintained. connections and takeoffs should be made in a neat and non-obstructing manner using structures made from steel and solidly anchored in the slabs or in footings specifically poured for the purpose. The area should be well illuminated to permit work and security inspections during darkness. Terminations, wires, bushings, switches and other distribution apparatus should be of the outdoor type or should be protected by enclosures. The entire substation area should be well grounded with a grounding matrix below grade over the entire area and the fence, equipment and apparatus should be well protected with lightning arresters. It is also recommended the entire system be the subject of a complete and detailed computer analysis. As the number of customers and the demands for more stable and reliable power services become greater, the ability to provide computer modeling of the effects of changes in the system takes on more dramatic importance. The ability to efficiently and economically provide for new customers and old alike is significantly improved when this computer modelling is used and the information it can provide is quickly, easily and readily available. Page 8 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. Ee CONCLUSIONS The costs of upgrading the existing GZU system are warranted since a newly configured system of the type recommended will provide a system that should be reliable and stable for years to come. The renovation of the power plant and improving the operations records and plant information will yield cost savings every time an extension must be made to service a new customer. The computer model will permit analysis of the problems currently plaguing the existing system and provide knowledgeable technicians and engineers with the tools and data necessary to prevent them from becoming problems in the new system. The growth, security and well-being of all those people dwelling within the reach of the GZU utility system will be enhanced and improved when this renovation and upgrade is completed. The funding of all the recommended actions should be undertaken. If all program elements cannot be funded at one time, the implementation of the improvements may be staged or phased to accommodate the upgrade. The phasing may be accomplished in any order, but to provide the most improvement in the system as soon as possible, the following phasing makes the most logical sense. RECOMMENDED PHASING PLAN FOR UPGRADING THE GZU ELECTRICAL SYSTEM PHASE ELEMENT TO BE COMPLETED 1 Outside Plant 2 Substation 3 Fuel System 4 Identification, Record Map & Computer Model Study 5 Revisions to System per Study Results 6 New Power Plant 7 New Sectionalizers and Loop Feeds Page 9 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. ae a a Se etc a re eee Note phase 7 was not included in this study or its cost estimates. The implementation of this phase is to make the reliability of service higher since faults or other problems within the system would be more closely isolated and fewer customers would be affected by outages due to equipment overloads or failures. There is no rigorous treatment provided here since there are numerous ways to build this increased reliability into the system. Such improvements must be made in conjunction and with the approval of the operators and power plant technicians. Page 10 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. G. APPENDIXES Page 11 UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. APPENDIX 1 - DRAWINGS Page 12 NEW NEUTRAL (POSITION #1) #0 ACSR y N NEUTRAL | @] Ae. N EXISTING PLAN 6 FT. CROSSARM NEW NEUTRAL (POSITION #2) . <a \—eyistine WOOD BRACES “*———NEW NEUTRAL (POSITION #1) #2 ACSR NEUTRAL SOLIDLY CLAMP #6 SOFT DRAWN BARE COPPER TO NEW DRIVEN GROUND ROD. NOTE: ELEVATION EITHER NEUTRAL POSITION MAY BE USED. (A 2 PHASE POLE CONFIGURATION XX) NO SCALE RELOCATE EXISTING B TO NEW PIN PROVIDE NEW AS SHOWN. NEUTRAL ON \ Pt NEW PIN. oA 9B $B gC | | 1 7 —#9 ACSR N at | | | | See 7 MOVE EXISTING $B 6 FT. CROSSARM ba CLAMP. SECURELY pe : TO NEUTRAL Me Map [ix aac \ JK EXISTING WOOD EXISTING BRACES 35 FT., CLASS 5 BURIED 6’—7’——+} #6 SOFT DRAWN BARE COPPER TO NEW DRIVEN ELEVATION GROUND ROD. NO SCALE (BY 3 PHASE POLE CONFIGURATION ey \—- ro M52-4 N MAY BE PLACED IA 23 INSTEAD OF | A 2 > AS SHOWN M52-3 OTES: He GROUND LINE NUMBERS AND LETTERS SHALL BE OF CUTOUT ALUMINUM OR ELECTROGALVANIZED SOFT STEEL, FASTENED TO POLE WITH GALVANIZED OR ALUMINUM, BARBED 1” ROUND HEAD NAILS. POLE LEGENDS TO BE 1-1/2" TO 3” HIGH. IF 3” CHARACTERS ARE USED, THEY SHOULD BE PLACED VERTICALLY INSTEAD OF AS SHOWN. "CN" TO BE 2” HIGH. POLE TO BE STAGGERED 30° FROM DIRECT FACING HIGHWAY. WHEN LINE CROSSES HIGHWAY, LEGEND SHOULD FACE ROAD. . ON POLES HAVING LIMITED CLIMBING SPACE DUE TO SPECIAL EQUIPMENT, POLE LEGEND SHOULD BE SO LOCATED AS TO LEAVE CLIMBING SPACE QUADRANT UNOBSTRUCTED. NEUTRAL IDENTIFICATION & POLE NUMBERING GUIDE SCALE: NO SCALE OA $B —#6 SDBC GROUND ELEVATION SINGLE PHASE TRANSFORMER on te 2 on oO an \XX_) SCALE: NO SCALE POLE NEUTRAL & HARDWARE SRO RUN EACH GROUND | SEPARATELY TO ROD & BOND. er 10'L. X 3/4°¢ COPPER-CLAD STEEL DRIVEN GROUND Sas EXISTING POLE A NO SCALE POLE GROUNDING, TYPICAL #6 SDBC (TYP.) ii GRADE -— PLASTIC GUARD SECURED TO POLE (TYPICAL) NOTES: 1. GROUND WIRE TO BE LOCATED ON SAME SIDE AS NEUTRAL CONDUCTOR & IN QUADRANT OPPOSITE CLIMBING SPACE OR POLE TOP PIN. 2. STAPLES ON GROUND WIRE SHALL BE 2'-0" APART, EXCEPT FOR A DISTANCE OF 8’-0" ABOVE GROUND & 8’-0” FROM TOP OF POLE WHERE THEY SHALL BE 6” APART. 3. GROUND WIRE TO CLEAR ALL HARDWARE BY 2” MIN. & SHALL BE STAPLED TO MAINTAIN THIS POSITION. SWITCHGEAR LIGHTNING ARRESTERS —- —, | reeper | FEEDER cB ‘ ca 4} ca / I | FEEDER R MI cs | ca # ELEVATION \ it ! ike, oul Te \ \ > : ae x 28282) L\ Set ———e Z] Pee es fle ~ “~ AY ta “> | Etoeepettter eee Sis2a ceeeeeeeee tS eee $ PB 4 o/® Ni © ¢ GROUND BUS roa | VA CONCRETE ri iy BASE PLAN SCHEMATIC SUB- STATION 7. 1 WOCCRLE UPGRADING FT. YUKON’S ELECTRICAL DISTRIBUTION SYSTEM December 1994 By FPE Roen Engineers, Inc. APPENDIX 2 - COST ESTIMATES Page 13 UPGRADE OUTSIDE PLANT ONLY PROJECT - Electrical Distribution System Upgrade Cost Estimate ; 10/11/94 CLIENT - GZU @ Ft. Yukon, Mr. David Thomas, Plant Manager : FPE Roen Project #GZU945033 = — DESCRIPTION W/O O'HEAD AND PROFIT Change Conns. @ Existing Xfmrs. Replace Existing Xfmrs Replace Primary Fuses Add Grounds Throughout Add Neutral Throughout Change Crossarm Arrangements DIVISION SUBTOTAL MOB/DEMOB DIVISION SUBTOTAL SUBTOTAL: SUBCONTRACTOR'S INDIRECT OVERHEAD: SUBCONTRACTOR'S PROFIT: TOTAL COST PLUS SUBCONTRACTOR'S OVERHEAD & PROFIT: GENERAL CONTRACTOR'S INDIRECT OVERHEAD: GENERAL CONTRACTOR'S PROFIT: UPGRADE PLANT & OPERATIONS PROJECT - Electrical Distribution System Upgrade Cost Estimate s 10/11/94 CLIENT - GZU @ Ft. Yukon, Mr. David Thomas, Plant Manager DESCRIPTION COST @ || W/O O'HEAD re 85162 AND PROETT Provide Identification Throughout Provide System Record Map 1 Perform Computer Models Study Revise System per Study Results Provide New Substation Renovate/Upgrade Fuel Storage Replace Power Plant DIVISION SUBTOTAL MOB/DEMOB DIVISION SUBTOTAL SUBTOTAL: r . $930,344 SUBCONTRACTOR'S INDIRECT OVERHEAD: . . $117,334 SUBCONTRACTOR'S PROFIT: . $137,469 TOTAL COST PLUS SUBCONTRACTOR'S OVERHEAD & PROFIT: $1,185,147 GENERAL CONTRACTOR'S INDIRECT OVERHEAD: 0% | 0% $59,257 GENERAL CONTRACTOR'S PROFIT: .0% 0% | $89,632 33 TOTAL COST PLUS OVERHEAD & PROFIT: I $1,304 TOTAL SYSTEM UPGRADE PROJECT - Electrical Distribution System Upgrade Cost Estimate CLIENT - GZU @ Ft. Yukon, Mr. David Thomas, Plant Manager _FPE Roen Project #GZU945033 DESCRIPTION Change Conns. @ Existing Xfmrs. Replace Existing Xfmrs Replace Primary Fuses Add Grounds Throughout Add Neutral Throughout Change Crossarm Arrangements Provide Identification Throughout |} = Provide System Record Map $10,324.00 Pertorm Computer Models Study | $6,194.40 Revise System per Study Results | $8,259.20 Provide New Substation | , r .0 | $30,972.00 Renovate/Upgrade Fuel Storage } .0 | $25,810.00 Replace Power Plant ‘ ¥ i 0 | exten $0.00 |} $0.00 | $0.00 | DIVISION SUBTOTAL MOB/DEMOB DIVISION SUBTOTAL , 10976.0 SUBTOTAL: z 11176.0 $1,139,823 SUBCONTRACTOR'S INDIRECT OVERHEAD: . \ | $142,128 SUBCONTRACTOR'S PROFIT: . ; | i $115,381 } $171,673 TOTAL COST PLUS SUBCONTRACTOR'S OVERHEAD & PROFIT: | $749,974 | $1 453,624 GENERAL CONTRACTOR'S INDIRECT OVERHEAD: 0% | 0% $37,499 | $72,681 INTRACTOR'S PROFIT: .0% | 0% $37,499 || $107,864 ee eee ee ere —,,