12-4 Kv Transformer Spec
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SPECIFICATIONS FOR THREE PHASE PAD-MOUNTED DISTRIBUTION TRANSFORMERS SUBMITTALS •
Shop Drawings: Include transformer ratings, features, accessories, compliance with the requirements specified herein, and conformance to the referenced standards and proposed testing to be conducted at the factory. Also include detailed and dimensioned plan, section and elevation drawings showing all components and features, recommended torque values for all electrical connections, complete wiring diagrams which designate factory and field wiring (if applicable), and complete equipment and material lists.
•
Compliance Certification: Provide Manufacturers signed certification that the equipment meets all of the requirements of these specifications and the contract documents.
CERTIFIED FACTORY TESTING All units shall be tested and certified for the following: • • • • • • • • • • •
No-load (Core) Losses at rated temperature (95°C). Full-load Winding Losses at rated temperature (95°C) and load. Percent Impedance Volts at rated temperature (95°C) and load. Excitation Current at 100% and 110% voltage. Winding Resistance measurement tests. Ratio tests for all tap settings. Polarity and Phase relation tests. Induced Potential tests. Full Wave and Reduced Wave Impulse tests. Applied Potential test. Insulation Power Factor test.
In addition, the manufacturer shall provide certification upon request for all design and other tests listed in Table 17 of ANSI C57.12.00 including verification that the design has passed Short Circuit Criteria per ANSI C57.12.00 and C57.12.90.
REFERENCE STANDARDS •
All three phase pad-mounted distribution transformers shall be designed, manufactured and tested in accordance with this specification and all applicable ANSI and NEMA Standards, latest revision.
•
All characteristics, definitions, and terminology, except as specifically covered in this specification, shall be in accordance with the latest revision of the following ANSI and NEMA standards: IEEE Standard C57.12.00 - General Requirements for Liquid-Immersed Distribution, Power and Regulating Transformers. IEEE Standard C57.12.26 - Pad-Mounted, Compartmental-Type, SelfCooled, Three-Phase Distribution Transformers For Use with Separable Insulated High-Voltage Connectors, High Voltage, 34500GrdY/19920 Volts and Below; 2500 KVA and Smaller. IEEE Standard C57.12.28 - Pad-Mounted Equipment - Enclosure Integrity. IEEE Standard C57.12.90 - IEEE Standard Test Code for LiquidImmersed Distribution, Power, and Regulating Transformers and IEEE Guide for Short-Circuit Testing of Distribution and Power Transformers. IEEE Standard C57.91 - Guide for Loading Mineral-Oil-Immersed Overhead and Pad-Mounted Transformers Rated 500 KVA and Less with 65°C or 55°C Average Winding Rise. IEEE Standard C57.92 - Guide for Loading Mineral-Oil-Immersed Power Transformers Up to and including 100 MVA with 65°C or 55°C Average Winding Rise.
•
The primary and secondary voltages and associated lightning impulse basic insulation levels (BIL) shall be in accordance with Table 1 below.
Table 1 Transformer and Connector High-Voltage Ratings and Electrical Characteristics Electrical Characteristics of the Completely Assembled High-Voltage Connectors 1.
Transformer
High-Voltage Ratings (volts) Single High-Voltage 2400 4160 4800 7200 12000 12470 13200 13800 14400 16430 4160GrdY/2400 8320GrdY/4800 12470GrdY/7200 13200GrdY/7620 13800GrdY/7970 22860GrdY/13200 23900GrdY/13800 24940GrdY/14400 34500GrdY/19920 Series-Multiple High-Voltage 4160GrdY/2400 x 12470GrdY/7200 4160GrdY/2400 x 13200GrdY/7600 4800 x 13200GrdY/7620 8320GrdY/4800 x 24940GrdY/14400 12470GrdY/7200 x 24940GrdY/14400 13200GrdY/7620 x 24940GrdY/14400 23900GrdY/13800 x 34500GrdY/19920
60-Hz dry one minute withstand (kV)
Minimum BIL 3. (kV)
High-Voltage Rating 2. Phase-to-Ground /Phase-to-Phase (kV)
BIL (kV)
60 60 60 75 95 95 95 95 95 95 60 75 95 95 95 125 125 125 150
8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 15.2/26.3 15.2/26.3 15.2/26.3 21.1/36.6
95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 125 125 125 150
34 34 34 34 34 34 34 34 34 34 344. 344. 344. 344. 344. 404. 404. 404. 50
60 x 95 60 x 95 60 x 95 75 x 125 95 x 125 95 x 125 125 x 150
8.3/14.4 8.3/14.4 8.3/14.4 15.2/26.3 15.2/26.3 15.2/26.3 21.1/36.6
95 95 95 125 125 125 150
34 34 34 40 40 40 50
1. For complete connector rating, see ANSI/IEEE 386. 2. Transformers shall be suitable for connectors with phase-to-ground or phase-toground/phase-to-phase high-voltage ratings as listed. 3. Surge Arrester insulation coordination may require higher BIL on multiple connection windings than indicated to achieve a minimum protective level margin of 20%. 4. Grounded-Wye connected transformers (non series-multiple) 1000kVA and below may be designed with reduced insulation at the neutral and tested in accordance with C57.12.26 paragraph 6.2 for deadfront units.
PRODUCTS This Bid Request is for the following three phase pad-mounted distribution transformer equipment: • Bid Item #1: Two (2) 2000kVA @ 65°C temperature rise, three phase pad-mounted transformer with a nominal primary voltage of 12,470GrdY/7,200V, and a nominal secondary voltage of 4,160GrdY/2,400V (Playtex Products and spare). • Bid Item #2: One (1) 1000kVA @ 65°C temperature rise, three phase pad-mounted transformer with a nominal primary voltage of 12,470GrdY/7,200V and a nominal secondary voltage of 4,160GrdY/2,400V (Playtex Apparel 3A & 3B). • Bid Item #3: One (1) 300kVA @ 65°C temperature rise, three phase pad-mounted transformer with a nominal primary voltage of 12,470GrdY/7,200V and a nominal secondary voltage of 4,160GrdY/2,400V (Court House). • Bid Item #4: One (1) 150kVA @ 65°C temperature rise, three phase pad-mounted transformer with a nominal primary voltage of 12,470GrdY/7,200V and a nominal secondary voltage of 4,160GrdY/2,400V (PNC Bank). GENERAL All three phase pad-mounted distribution transformers shall be the completely factory fabricated compartmental type, mineral oil-immersed, self-cooled, with loop-feed dead-front primary winding connections and radial-feed dead-front secondary winding connections (for transformers with ratings less than or equal to 1000kVA), two (2) each 2 1/2% primary winding taps above and below nominal voltage rating with an external tap switch for de-energized operation, and provided with integral primary voltage protection in the form of appropriately sized load break bayonet type expulsion fuses in series with backup current limiting fuses under oil.
MANUFACTURES QUALIFICATIONS Only Firms experienced in manufacturing equipment of the types and capacities indicated that are able to show evidence of continuous engagement in the manufacture of pad-mounted transformers for the last five (5) years will be considered. WARRANTY All three phase pad-mounted transformers shall be warranted to be free from defects in material and workmanship for a period of twelve (12) months from the date of installation or eighteen (18) months from the date of delivery whichever is longer. AWARD OF BID The City of Dover reserves the right not to award the Contract to the lowest bidder, based upon delivery schedule, loss evaluation, qualifications of the bidder/manufacturer, technical issues encountered during bid evaluation, compliance with the City’s Specifications and Contract Documents, and the Terms and Conditions of Sale. RATINGS •
The average winding temperature rise above a 30°C 24 hour average with a 40°C peak ambient temperature, when tested at the transformer rating, shall not exceed 65°C.
•
The percent impedance voltage, as measured on the rated nominal voltage connection, shall be per IEEE C57.12.26, paragraph 5.1. Manufacturing tolerance for impedance values shall be per ANSI C57.12.00, Table 19.
KVA Rating 45 – 75 112.5 – 300 500 750 – 2500
Table 2 Percent Impedance Voltage Low-Voltage Rating < 4,160 GrdY/2400V With High Voltage Rating shown below < 150 kV BIL 200 kV BIL 250 kV BIL 1.00 - 5.00 7.25 7.75 1.20 – 6.0 7.25 7.75 1.50 - 7.00 7.25 7.75 5.75 7.25 7.75
CORE AND COIL ASSEMBLY •
The core and coils shall be vacuum processed to ensure maximum penetration of insulating fluid into the coil insulation system. The transformer shall be filled with preheated, filtered and degassed insulating fluid. The core shall be manufactured from burr-free, grain-oriented or amorphous silicon steel and shall be precisely stacked to eliminate gaps in the corner joints. The winding coils shall be insulated with diamond pattern, epoxy-coated insulating paper, which shall be thermally cured under pressure to ensure proper bonding of the winding conductor and paper insulation.
•
Copper primary and secondary windings are preferred. Substitution of aluminum windings may be considered if they provide a substantial cost savings when transformer first cost and loss-evaluated cost are considered.
•
The transformer low voltage windings shall have a three phase, 60 Hz rating equivalent to the transformer primary windings.
GENERAL Sealed pad-mounted transformer tanks shall be provided with the necessary cooling radiators and individual high voltage and low voltage cable compartments separated by a steel barrier. The enclosure shall have no exposed removable parts, no exposed openings, be tamper proof, weather proof, and suitable for pad mounting. Cable compartment doors, door-sills and hoods shall be removable. TANK AND TERMINAL COMPARTMENT •
The terminal compartment depth shall be in accordance with Figure 7 of ANSI C57.12.26.
•
Doors: Separate doors shall be provided for high and low voltage cable terminal compartments with mechanical interlocks so that access to the high voltage compartment is prevented unless the low voltage compartment is open. Doors to include open position door-stops and stainless steel hinges and pins. The low voltage compartment door shall incorporate a three-point locking mechanism to assure a tight and secure door closing, and latching handle with provisions for a single padlock to secure both compartments. In addition to the regular locking provision, all access doors and hoods shall be secured by a recessed, captive pentahead bolt that meets the dimensions set forth in ANSI C57.12.28.
•
The tank must be welded using precision cut, cold-rolled steel and equipped with extra-heavy duty, welded-in-place lifting lugs and jacking pads. The tank base must be designed to allow skidding or rolling in any direction.
•
The transformer shall be of sealed tank construction with sufficient strength to withstand a pressure of 7 psig without permanent distortion, and 15 psig without rupturing or affecting cabinet security per ANSI C57.12.26 paragraph 7.5.2. The tank shall include a pressure relief valve with a flow at 15 psig of 35 SCFM minimum, or as required to meet the listing of the insulating fluid. The venting and sealing characteristics shall be as follows: 9 Cracking Pressure: 10 psig ± 2 psig 9 Resealing Pressure: 6 psig minimum 9 Zero leakage from resealing pressure to -8 psig
•
The tank shall be cleaned with an alkaline cleaning agent to remove grease and oil. An iron phosphate coating shall then be chemically bonded to the metal to assure coating adhesion and to retard corrosion. The tank shall be primed with an electrodeposited powder epoxy to provide a barrier against moisture, salt, and corrosives. The tank shall then be coated with two coats of Standard Munsell No. 7GY3.29/1.5 Green. The tank coating shall meet all requirements in ANSI C57.12.28 including: 9 9 9 9 9 9 9
Salt Spray Test Crosshatch Adhesion Test Humidity Test Impact Test Oil Resistance Test Ultraviolet Accelerated Weathering Test Abrasion Resistance - Taber Abraser
•
The transformers tanks shall have a catalytic epoxy coal tar composition applied to the bottom for extra protection against corrosion.
•
The pad-mounted equipment shall meet the requirements for tamper resistance set forth in ANSI C57.12.28 including but not limited to the pry test, pull test, and wire probe test.
•
The tank shall be complete with an anodized aluminum or stainless steel laser engraved or stamped nameplate. This nameplate shall meet ANSI C57.12.00 for Nameplate B.
INSULATING FLUID •
The dielectric coolant in the transformer must be new, highly refined and inhibited 10 C mineral oil and meet the minimum requirements as specified in Table 1, “Functional Property Requirements”, of ASTM D3487 and ANSI C57.106.
•
All transformer oil must be bulk tested for polychlorinated biphenyls (PCBs) per ASTM D4059 and certified as having no detectable level of PCBs. The pad- mounted transformers shall be certified and labeled nonPCB, and provided with a certified test report to ASTM standards for documenting insulating oil, color, acidity, dielectric strength, interfacial tension, visual appearance, and water content.
HIGH VOLTAGE COMPARTMENT •
The voltage provided and the basic insulation level (BIL) shall be in accordance with Table 1.
•
The pad mounted transformers shall have primary winding connections constructed for dead front loop feed operation and supplied with six (6) universal deep well bushing assemblies and six (6) universal 200A loadbreak bushing inserts capable of accepting ESNA standard, 15kV class, 200A load break elbows conforming to ANSI/IEEE 386. The bushing well assemblies shall be externally removable and clamped and have an integral molded semi-conductive shield. These assemblies, with the appropriate 200A load-break bushing inserts shall allow for the use of bushing position elbow-type surge arrestors.
•
The pad-mounted transformers shall have separate HV and LV winding external fully insulated neutral bushings provided with removable grounding connections between the HV and LV neutral bushings and the NEMA standard transformer ground pad to facilitate transformer testing.
•
The bushing heights shall be in accordance with Figure 7 of ANSI C57.12.26.
•
Cable accessory parking stands shall be provided and shall be located such that the separable insulated load break connectors that are designed for energized operation with the transformer in its permanent location can be operated by hot-line tools.
LOW VOLTAGE COMPARTMENT •
The voltage provided and the basic insulation level (BIL) shall be in accordance with Table 1.
•
The pad mounted transformers with ratings less than or equal to 1000kVA shall have secondary winding connections constructed for radial-feed dead-front operation and supplied with three (3) universal deep well bushing assemblies and three (3) universal 200A load-break bushing inserts capable of accepting ESNA standard, 15kV class, 200A load break elbows conforming to ANSI/IEEE 386. The bushing well assemblies shall be externally removable and clamped and have an integral molded semiconductive shield.
•
Cable accessory parking stands shall be provided and shall be located such that the separable insulated load break connectors that are designed for energized operation with the transformer in its permanent location can be operated by hot-line tools.
•
The transformer low voltage phase and neutral bushings for the units rated 2000kVA shall be one-piece epoxy, porcelain, or fiberglass polyester material with silver-plated copper flat pad terminal spades and NEMA standard 4-hole drilling. The low-voltage bushings shall be the bolted type with external clamping. The low-voltage bushing terminals shall be in accordance with Figure 9 of ANSI C57.12.26.
•
If the transformer is equipped with threaded stud-type phase and neutral terminals, these terminals shall be provided with silver-plated copper flat pad stud connectors with NEMA standard 4-hole drilling installed for the phase and neutral terminals.
•
The configuration of the transformer low voltage bushings shall be in accordance with ANSI C57.12.26, Figure 8. The secondary bushings shall be replaceable utilizing the access provided or through the removal of the sealed tank access cover.
•
The bushing heights shall be in accordance with Figure 7 of ANSI C57.12.26.
PROTECTION •
The over-current protection scheme provided with the transformer shall consist of the following attributes. If for any reason a protection scheme other than the following is required it shall be clearly stated as an exception on the bid.
•
The transformer primary shall include load break Bay-O-Net fuse assemblies with flapper valves and drip shields to minimize oil spillage. Over-current protection shall be provided by Bay-O-Net expulsion fuses mounted in series with partial range under-oil ELSP (or equivalent) current-limiting fuses with an interrupting rating of 50,000 A. This fusing scheme is intended to provide full range protection for system reliability and safety of operating personnel where distribution primary single phase to ground fault currents may exceed 3500A.
ACCESSORIES The following standard accessories shall be provided: • • • • • • •
Four (4) each lifting lugs and jacking plates. Penta-head bolted doors and hoods w/ bolt guard 1.0” upper fill plug 1.0” drain/sampling valve in the low voltage compartment Automatic pressure relief device 20” deep HV and LV terminal compartments Stainless steel NEMA Standard two hole ground pads
The following optional accessories shall be provided: • • • • • •
Liquid level gauge Pressure/vacuum gauge Dial type thermometer High voltage (and low voltage where applicable) 200A universal bushing well inserts Ground connectors Touch-up paint
LOSS EVALUATION The following penalties will be assigned to transformer losses during the bid evaluation process: • $4,000/kW for No-load (Core) losses • $1000/kW for full load (OA) winding losses.
HAZARD ALERTING SIGNS
•
The exterior of the pad-mounted enclosure shall be provided with “WARNING-KEEP OUT-HAZARDOUS VOLTAGE INSIDE- CAN SHOCK, BURN OR CAUSE DEATH” signs.
•
The interior of the pad-mounted enclosure shall be provided with a “DANGER-HAZARDOUS VOLTAGE-FAILURE TO FOLLOW THESE INSTRUCTIONS WILL LIKELY CAUSE SHOCK, BURNS OR DEATH” sign. The text will further indicate that operating personnel must know and obey the employer’s work rules, know the hazards involved, and use proper protective tools to work on this equipment.
MISCELLANEOUS Operation and Maintenance Manual: provide 8-1/2” x 11” bound manual including all shop drawing information, spare parts list with model numbers, local service facilities, and recommended maintenance and testing procedures.
DELIVERY Each individual pad-mounted transformer unit shall be bonded or bolted to a wooden pallet made with “4 by 4 lumber“ minimum. To facilitate the City’s unloading from the delivery truck and handling by fork-lift or aerial lifts/derrick and slings, the pad-mounted transformers must be shipped on an open type truck. Each unit shall be protected from paint damage while in transit.
Transformers shipped such that they cannot be lifted in this manner will not be accepted.
Shop Drawings: Include transformer ratings, features, accessories, compliance with the requirements specified herein, and conformance to the referenced standards and proposed testing to be conducted at the factory. Also include detailed and dimensioned plan, section and elevation drawings showing all components and features, recommended torque values for all electrical connections, complete wiring diagrams which designate factory and field wiring (if applicable), and complete equipment and material lists.
•
Compliance Certification: Provide Manufacturers signed certification that the equipment meets all of the requirements of these specifications and the contract documents.
CERTIFIED FACTORY TESTING All units shall be tested and certified for the following: • • • • • • • • • • •
No-load (Core) Losses at rated temperature (95°C). Full-load Winding Losses at rated temperature (95°C) and load. Percent Impedance Volts at rated temperature (95°C) and load. Excitation Current at 100% and 110% voltage. Winding Resistance measurement tests. Ratio tests for all tap settings. Polarity and Phase relation tests. Induced Potential tests. Full Wave and Reduced Wave Impulse tests. Applied Potential test. Insulation Power Factor test.
In addition, the manufacturer shall provide certification upon request for all design and other tests listed in Table 17 of ANSI C57.12.00 including verification that the design has passed Short Circuit Criteria per ANSI C57.12.00 and C57.12.90.
REFERENCE STANDARDS •
All three phase pad-mounted distribution transformers shall be designed, manufactured and tested in accordance with this specification and all applicable ANSI and NEMA Standards, latest revision.
•
All characteristics, definitions, and terminology, except as specifically covered in this specification, shall be in accordance with the latest revision of the following ANSI and NEMA standards: IEEE Standard C57.12.00 - General Requirements for Liquid-Immersed Distribution, Power and Regulating Transformers. IEEE Standard C57.12.26 - Pad-Mounted, Compartmental-Type, SelfCooled, Three-Phase Distribution Transformers For Use with Separable Insulated High-Voltage Connectors, High Voltage, 34500GrdY/19920 Volts and Below; 2500 KVA and Smaller. IEEE Standard C57.12.28 - Pad-Mounted Equipment - Enclosure Integrity. IEEE Standard C57.12.90 - IEEE Standard Test Code for LiquidImmersed Distribution, Power, and Regulating Transformers and IEEE Guide for Short-Circuit Testing of Distribution and Power Transformers. IEEE Standard C57.91 - Guide for Loading Mineral-Oil-Immersed Overhead and Pad-Mounted Transformers Rated 500 KVA and Less with 65°C or 55°C Average Winding Rise. IEEE Standard C57.92 - Guide for Loading Mineral-Oil-Immersed Power Transformers Up to and including 100 MVA with 65°C or 55°C Average Winding Rise.
•
The primary and secondary voltages and associated lightning impulse basic insulation levels (BIL) shall be in accordance with Table 1 below.
Table 1 Transformer and Connector High-Voltage Ratings and Electrical Characteristics Electrical Characteristics of the Completely Assembled High-Voltage Connectors 1.
Transformer
High-Voltage Ratings (volts) Single High-Voltage 2400 4160 4800 7200 12000 12470 13200 13800 14400 16430 4160GrdY/2400 8320GrdY/4800 12470GrdY/7200 13200GrdY/7620 13800GrdY/7970 22860GrdY/13200 23900GrdY/13800 24940GrdY/14400 34500GrdY/19920 Series-Multiple High-Voltage 4160GrdY/2400 x 12470GrdY/7200 4160GrdY/2400 x 13200GrdY/7600 4800 x 13200GrdY/7620 8320GrdY/4800 x 24940GrdY/14400 12470GrdY/7200 x 24940GrdY/14400 13200GrdY/7620 x 24940GrdY/14400 23900GrdY/13800 x 34500GrdY/19920
60-Hz dry one minute withstand (kV)
Minimum BIL 3. (kV)
High-Voltage Rating 2. Phase-to-Ground /Phase-to-Phase (kV)
BIL (kV)
60 60 60 75 95 95 95 95 95 95 60 75 95 95 95 125 125 125 150
8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 8.3/14.4 15.2/26.3 15.2/26.3 15.2/26.3 21.1/36.6
95 95 95 95 95 95 95 95 95 95 95 95 95 95 95 125 125 125 150
34 34 34 34 34 34 34 34 34 34 344. 344. 344. 344. 344. 404. 404. 404. 50
60 x 95 60 x 95 60 x 95 75 x 125 95 x 125 95 x 125 125 x 150
8.3/14.4 8.3/14.4 8.3/14.4 15.2/26.3 15.2/26.3 15.2/26.3 21.1/36.6
95 95 95 125 125 125 150
34 34 34 40 40 40 50
1. For complete connector rating, see ANSI/IEEE 386. 2. Transformers shall be suitable for connectors with phase-to-ground or phase-toground/phase-to-phase high-voltage ratings as listed. 3. Surge Arrester insulation coordination may require higher BIL on multiple connection windings than indicated to achieve a minimum protective level margin of 20%. 4. Grounded-Wye connected transformers (non series-multiple) 1000kVA and below may be designed with reduced insulation at the neutral and tested in accordance with C57.12.26 paragraph 6.2 for deadfront units.
PRODUCTS This Bid Request is for the following three phase pad-mounted distribution transformer equipment: • Bid Item #1: Two (2) 2000kVA @ 65°C temperature rise, three phase pad-mounted transformer with a nominal primary voltage of 12,470GrdY/7,200V, and a nominal secondary voltage of 4,160GrdY/2,400V (Playtex Products and spare). • Bid Item #2: One (1) 1000kVA @ 65°C temperature rise, three phase pad-mounted transformer with a nominal primary voltage of 12,470GrdY/7,200V and a nominal secondary voltage of 4,160GrdY/2,400V (Playtex Apparel 3A & 3B). • Bid Item #3: One (1) 300kVA @ 65°C temperature rise, three phase pad-mounted transformer with a nominal primary voltage of 12,470GrdY/7,200V and a nominal secondary voltage of 4,160GrdY/2,400V (Court House). • Bid Item #4: One (1) 150kVA @ 65°C temperature rise, three phase pad-mounted transformer with a nominal primary voltage of 12,470GrdY/7,200V and a nominal secondary voltage of 4,160GrdY/2,400V (PNC Bank). GENERAL All three phase pad-mounted distribution transformers shall be the completely factory fabricated compartmental type, mineral oil-immersed, self-cooled, with loop-feed dead-front primary winding connections and radial-feed dead-front secondary winding connections (for transformers with ratings less than or equal to 1000kVA), two (2) each 2 1/2% primary winding taps above and below nominal voltage rating with an external tap switch for de-energized operation, and provided with integral primary voltage protection in the form of appropriately sized load break bayonet type expulsion fuses in series with backup current limiting fuses under oil.
MANUFACTURES QUALIFICATIONS Only Firms experienced in manufacturing equipment of the types and capacities indicated that are able to show evidence of continuous engagement in the manufacture of pad-mounted transformers for the last five (5) years will be considered. WARRANTY All three phase pad-mounted transformers shall be warranted to be free from defects in material and workmanship for a period of twelve (12) months from the date of installation or eighteen (18) months from the date of delivery whichever is longer. AWARD OF BID The City of Dover reserves the right not to award the Contract to the lowest bidder, based upon delivery schedule, loss evaluation, qualifications of the bidder/manufacturer, technical issues encountered during bid evaluation, compliance with the City’s Specifications and Contract Documents, and the Terms and Conditions of Sale. RATINGS •
The average winding temperature rise above a 30°C 24 hour average with a 40°C peak ambient temperature, when tested at the transformer rating, shall not exceed 65°C.
•
The percent impedance voltage, as measured on the rated nominal voltage connection, shall be per IEEE C57.12.26, paragraph 5.1. Manufacturing tolerance for impedance values shall be per ANSI C57.12.00, Table 19.
KVA Rating 45 – 75 112.5 – 300 500 750 – 2500
Table 2 Percent Impedance Voltage Low-Voltage Rating < 4,160 GrdY/2400V With High Voltage Rating shown below < 150 kV BIL 200 kV BIL 250 kV BIL 1.00 - 5.00 7.25 7.75 1.20 – 6.0 7.25 7.75 1.50 - 7.00 7.25 7.75 5.75 7.25 7.75
CORE AND COIL ASSEMBLY •
The core and coils shall be vacuum processed to ensure maximum penetration of insulating fluid into the coil insulation system. The transformer shall be filled with preheated, filtered and degassed insulating fluid. The core shall be manufactured from burr-free, grain-oriented or amorphous silicon steel and shall be precisely stacked to eliminate gaps in the corner joints. The winding coils shall be insulated with diamond pattern, epoxy-coated insulating paper, which shall be thermally cured under pressure to ensure proper bonding of the winding conductor and paper insulation.
•
Copper primary and secondary windings are preferred. Substitution of aluminum windings may be considered if they provide a substantial cost savings when transformer first cost and loss-evaluated cost are considered.
•
The transformer low voltage windings shall have a three phase, 60 Hz rating equivalent to the transformer primary windings.
GENERAL Sealed pad-mounted transformer tanks shall be provided with the necessary cooling radiators and individual high voltage and low voltage cable compartments separated by a steel barrier. The enclosure shall have no exposed removable parts, no exposed openings, be tamper proof, weather proof, and suitable for pad mounting. Cable compartment doors, door-sills and hoods shall be removable. TANK AND TERMINAL COMPARTMENT •
The terminal compartment depth shall be in accordance with Figure 7 of ANSI C57.12.26.
•
Doors: Separate doors shall be provided for high and low voltage cable terminal compartments with mechanical interlocks so that access to the high voltage compartment is prevented unless the low voltage compartment is open. Doors to include open position door-stops and stainless steel hinges and pins. The low voltage compartment door shall incorporate a three-point locking mechanism to assure a tight and secure door closing, and latching handle with provisions for a single padlock to secure both compartments. In addition to the regular locking provision, all access doors and hoods shall be secured by a recessed, captive pentahead bolt that meets the dimensions set forth in ANSI C57.12.28.
•
The tank must be welded using precision cut, cold-rolled steel and equipped with extra-heavy duty, welded-in-place lifting lugs and jacking pads. The tank base must be designed to allow skidding or rolling in any direction.
•
The transformer shall be of sealed tank construction with sufficient strength to withstand a pressure of 7 psig without permanent distortion, and 15 psig without rupturing or affecting cabinet security per ANSI C57.12.26 paragraph 7.5.2. The tank shall include a pressure relief valve with a flow at 15 psig of 35 SCFM minimum, or as required to meet the listing of the insulating fluid. The venting and sealing characteristics shall be as follows: 9 Cracking Pressure: 10 psig ± 2 psig 9 Resealing Pressure: 6 psig minimum 9 Zero leakage from resealing pressure to -8 psig
•
The tank shall be cleaned with an alkaline cleaning agent to remove grease and oil. An iron phosphate coating shall then be chemically bonded to the metal to assure coating adhesion and to retard corrosion. The tank shall be primed with an electrodeposited powder epoxy to provide a barrier against moisture, salt, and corrosives. The tank shall then be coated with two coats of Standard Munsell No. 7GY3.29/1.5 Green. The tank coating shall meet all requirements in ANSI C57.12.28 including: 9 9 9 9 9 9 9
Salt Spray Test Crosshatch Adhesion Test Humidity Test Impact Test Oil Resistance Test Ultraviolet Accelerated Weathering Test Abrasion Resistance - Taber Abraser
•
The transformers tanks shall have a catalytic epoxy coal tar composition applied to the bottom for extra protection against corrosion.
•
The pad-mounted equipment shall meet the requirements for tamper resistance set forth in ANSI C57.12.28 including but not limited to the pry test, pull test, and wire probe test.
•
The tank shall be complete with an anodized aluminum or stainless steel laser engraved or stamped nameplate. This nameplate shall meet ANSI C57.12.00 for Nameplate B.
INSULATING FLUID •
The dielectric coolant in the transformer must be new, highly refined and inhibited 10 C mineral oil and meet the minimum requirements as specified in Table 1, “Functional Property Requirements”, of ASTM D3487 and ANSI C57.106.
•
All transformer oil must be bulk tested for polychlorinated biphenyls (PCBs) per ASTM D4059 and certified as having no detectable level of PCBs. The pad- mounted transformers shall be certified and labeled nonPCB, and provided with a certified test report to ASTM standards for documenting insulating oil, color, acidity, dielectric strength, interfacial tension, visual appearance, and water content.
HIGH VOLTAGE COMPARTMENT •
The voltage provided and the basic insulation level (BIL) shall be in accordance with Table 1.
•
The pad mounted transformers shall have primary winding connections constructed for dead front loop feed operation and supplied with six (6) universal deep well bushing assemblies and six (6) universal 200A loadbreak bushing inserts capable of accepting ESNA standard, 15kV class, 200A load break elbows conforming to ANSI/IEEE 386. The bushing well assemblies shall be externally removable and clamped and have an integral molded semi-conductive shield. These assemblies, with the appropriate 200A load-break bushing inserts shall allow for the use of bushing position elbow-type surge arrestors.
•
The pad-mounted transformers shall have separate HV and LV winding external fully insulated neutral bushings provided with removable grounding connections between the HV and LV neutral bushings and the NEMA standard transformer ground pad to facilitate transformer testing.
•
The bushing heights shall be in accordance with Figure 7 of ANSI C57.12.26.
•
Cable accessory parking stands shall be provided and shall be located such that the separable insulated load break connectors that are designed for energized operation with the transformer in its permanent location can be operated by hot-line tools.
LOW VOLTAGE COMPARTMENT •
The voltage provided and the basic insulation level (BIL) shall be in accordance with Table 1.
•
The pad mounted transformers with ratings less than or equal to 1000kVA shall have secondary winding connections constructed for radial-feed dead-front operation and supplied with three (3) universal deep well bushing assemblies and three (3) universal 200A load-break bushing inserts capable of accepting ESNA standard, 15kV class, 200A load break elbows conforming to ANSI/IEEE 386. The bushing well assemblies shall be externally removable and clamped and have an integral molded semiconductive shield.
•
Cable accessory parking stands shall be provided and shall be located such that the separable insulated load break connectors that are designed for energized operation with the transformer in its permanent location can be operated by hot-line tools.
•
The transformer low voltage phase and neutral bushings for the units rated 2000kVA shall be one-piece epoxy, porcelain, or fiberglass polyester material with silver-plated copper flat pad terminal spades and NEMA standard 4-hole drilling. The low-voltage bushings shall be the bolted type with external clamping. The low-voltage bushing terminals shall be in accordance with Figure 9 of ANSI C57.12.26.
•
If the transformer is equipped with threaded stud-type phase and neutral terminals, these terminals shall be provided with silver-plated copper flat pad stud connectors with NEMA standard 4-hole drilling installed for the phase and neutral terminals.
•
The configuration of the transformer low voltage bushings shall be in accordance with ANSI C57.12.26, Figure 8. The secondary bushings shall be replaceable utilizing the access provided or through the removal of the sealed tank access cover.
•
The bushing heights shall be in accordance with Figure 7 of ANSI C57.12.26.
PROTECTION •
The over-current protection scheme provided with the transformer shall consist of the following attributes. If for any reason a protection scheme other than the following is required it shall be clearly stated as an exception on the bid.
•
The transformer primary shall include load break Bay-O-Net fuse assemblies with flapper valves and drip shields to minimize oil spillage. Over-current protection shall be provided by Bay-O-Net expulsion fuses mounted in series with partial range under-oil ELSP (or equivalent) current-limiting fuses with an interrupting rating of 50,000 A. This fusing scheme is intended to provide full range protection for system reliability and safety of operating personnel where distribution primary single phase to ground fault currents may exceed 3500A.
ACCESSORIES The following standard accessories shall be provided: • • • • • • •
Four (4) each lifting lugs and jacking plates. Penta-head bolted doors and hoods w/ bolt guard 1.0” upper fill plug 1.0” drain/sampling valve in the low voltage compartment Automatic pressure relief device 20” deep HV and LV terminal compartments Stainless steel NEMA Standard two hole ground pads
The following optional accessories shall be provided: • • • • • •
Liquid level gauge Pressure/vacuum gauge Dial type thermometer High voltage (and low voltage where applicable) 200A universal bushing well inserts Ground connectors Touch-up paint
LOSS EVALUATION The following penalties will be assigned to transformer losses during the bid evaluation process: • $4,000/kW for No-load (Core) losses • $1000/kW for full load (OA) winding losses.
HAZARD ALERTING SIGNS
•
The exterior of the pad-mounted enclosure shall be provided with “WARNING-KEEP OUT-HAZARDOUS VOLTAGE INSIDE- CAN SHOCK, BURN OR CAUSE DEATH” signs.
•
The interior of the pad-mounted enclosure shall be provided with a “DANGER-HAZARDOUS VOLTAGE-FAILURE TO FOLLOW THESE INSTRUCTIONS WILL LIKELY CAUSE SHOCK, BURNS OR DEATH” sign. The text will further indicate that operating personnel must know and obey the employer’s work rules, know the hazards involved, and use proper protective tools to work on this equipment.
MISCELLANEOUS Operation and Maintenance Manual: provide 8-1/2” x 11” bound manual including all shop drawing information, spare parts list with model numbers, local service facilities, and recommended maintenance and testing procedures.
DELIVERY Each individual pad-mounted transformer unit shall be bonded or bolted to a wooden pallet made with “4 by 4 lumber“ minimum. To facilitate the City’s unloading from the delivery truck and handling by fork-lift or aerial lifts/derrick and slings, the pad-mounted transformers must be shipped on an open type truck. Each unit shall be protected from paint damage while in transit.
Transformers shipped such that they cannot be lifted in this manner will not be accepted.
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