APPENDIX C SINGLE PHASE UNDERGROUND TRANSFORMERS SINGLE PHASE UNDERGROUND TRANSFORMER

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1 SINGLE PHASE UNDERGROUND TRANSFORMER PART 1 - GENERAL 1.01 DESCRIPTION A. This specification provides the requirements for the design manufacturing and testing of three phase, 60 Hertz, liquid-filled, self-cooled, vault-type distribution transformers. B. This specification applies to all the electrical and mechanical features of three phases 12,000 volt primary, 60 Hz, liquid-filled, self-cooled, underground-type vault transformer for installation in below ground enclosures, which will be subject to occasional flooding. The transformers are intended to be operated while completely submerged in water, and/or require minimum effort to re-establish service after a flood. The successful bidder shall provide all work and material to design, fabricate, test, and deliver the specified equipment along with any drawings, manuals, or other documents required. C. The vendor shall furnish underground transformers as specified herein and in the Transformer Equipment Schedule. D. Bidders shall be required to submit bid with product cut sheet with ratings and listed dimensions (hard and soft copy). All sub-surface transformer, 1000KVA and below shall fit into a deepened #7 box (4 6 x8 6 x7 6 ) REFERENCES A. IEEE C , IEEE Standard General Requirements for Liquid Immersed Distribution, Power, and Regulating Transformers. B. IEEE C , Safety Requirements for Transformers 230 kv and Below. C. IEEE C , Underground-Type Three-Phase Distribution Transformers. D. IEEE C , IEEE Standard for Submersible Equipment Enclosure Integrity. E. IEEE C , Terminal Markings and Connections for Distribution and Power Transformers. F. IEEE C , Standard Terminology for Power and Distribution Transformers. G. IEEE C , Standard Test code for Liquid-Immersed Distribution, Power, and Regulating Transformers and IEEE Guide for Short-Circuit Testing of Distribution and Power Transformers. H. IEEE 386, IEEE Standard for Separable Insulated Connector Systems for Power Distribution systems above 600V. Page 1 of 8

2 I. ASTM D3487, Standard Specification for Mineral Insulating Oil. J. ASTM D6871, Standard Specification for Natural (Vegetable Oil) Ester Fluids Used in Electrical apparatus SERVICE CONDITIONS The equipment shall be capable of operating in accordance with the nameplate rating as shown on design drawings when operated under the service conditions and defined in referenced standards. The transformer shall be designed for frequent or occasional submerged operation SUBMITTALS A. The manufacturer shall submit with their bid the following technical information on each transformer size/rating being proposed: 1) A dimensioned outline drawing showing maximum dimensions and location of exterior mounted devices. 2) Transformer net weights (approximate). 3) The following performance data: Rating Temperature rise at rated load Guaranteed No-load and Guaranteed total losses Percent regulation at rated load 100% power Percent regulation at rated load 80% power Percent impedance B. The manufacturer shall submit a copy of their quality assurance manual used in the manufacture of the equipment being supplied. The quality assurance information shall include the certification process for welding performed by shop personnel. C. It shall be expressly understood that the technical information submitted with the bid, as furnished by the successful manufacturer, shall constitute guarantees, with variance only insofar as allowable by applicable ANSI, IEEE, and other Industry Standard tolerances. D. Losses quoted should be realistic values based on experience with tested designs, and therefore can be guaranteed with certainty for the units to be supplied SEISMIC REQUIREMENTS A. The equipment, accessories, and supporting structures should be designed such that there will be no damage, and the equipment should remain operational, during and following an earthquake with a base motion of 0.25g horizontal and 0.20g vertical, acting simultaneously. Page 2 of 8

3 B. The primary steady state stresses shall be within the allowable working stress limits accepted as good practice and set forth in the appropriate design standards. The primary steady state stresses shall include those originating from gravity loads, operating loads, and operating temperatures and should be combined with the seismic stresses. PART 2 - PRODUCTS 2.01 GENERAL A. The transformer shall be built, tested, and delivered in accordance with the industry standards as applicable as defined in Section 1.02 unless specifically addressed otherwise in this specification or in writing by the Engineer. The manufacturer shall be: ABB, Howard Industry, GE or approved equal. B. The manufacturer shall have an established welding certification and quality assurance program in place for all performed welding in the manufacturing of the transformer. C. The transformer rating shall be as shown on the design drawing kva rating shall be based on 55 degree C or 65 degree rise. D. Windings shall be copper. E. Transformer shall be 75KVA. F. The high-voltage primary winding shall be: 12,000 volts G. The insulation class shall be in accordance with IEEE C and IEEE C and the minimum BIL rating of the primary windings and bushings shall be in accordance with the table below. Primary Voltage Class BIL Rating 12,000 volts 15kV 95 kv H. The low voltage shall be 208 Grd Y/120 volts I. The insulation class shall be in accordance with IEEE C and IEEE C and the minimum BIL rating of the secondary windings and bushings shall be in accordance with the table below: Secondary Voltage Class BIL Rating 120/240 volts 1.2 kv 30 kv J. The transformer shall have an externally operable manual tap changer providing full capacity taps. Two 2-1/2% taps above and two 2-1/2% taps below are required on the high voltage windings. J. The transformers minimum impedances shall be specified below: Page 3 of 8

4 75 kva 1.5% Any units received with impedance values less than the listed values may be rejected by the Engineer CONSTRUCTION A. The primary high-voltage bushings, parking stands, and secondary voltage bushings and other accessories shall be located on the cover as specified in Figure 2 of IEEE C The manufacturer shall submit drawings for approval showing the location of these items with the bid response. B. The transformer tank shall be steel and shall have a minimum thickness of ¼ inch. The radiators shall be carbon steel or stainless steel construction. Carbon steel radiators have a thickness of 5/32 inch. C. All exterior surfaces shall be coated using a system of coordinated and thoroughly tested materials and application techniques that will assure long life under submersed or partially submersed conditions in accordance with IEEE C Special attention shall be given to welds, seams, edges, and rough spots. D. No portion of the tank or protruding appurtenances shall trap or hold water. E. The hand-hole shall be bolted flanged type. The hand-hole should provide accessibility to secondary bushings and internal current limiting fuses. F. Lifting lugs shall be designed and located on the tank to avoid interference between lifting slings and any attachments on the transformer, and to avoid scratching or marring the transformer coating. The transformer shall contain suitable jacking and rolling facilities. G. All nuts, bolts, studs, and screws shall conform to the ANSI standards of pitch, thread shapes, dimensions, and tolerances. H. The maximum average sound level as measured per IEEE C shall be in accordance with IEEE C I. Each transformer shall be supplied with six (3) primary bushing wells (1 per phase) per IEEE C Each bushing well shall be rated for the primary voltage and 200- ampere continuous. They shall comply with all applicable requirements and Figure 3 of IEEE 386. The transformer primary bushing wells shall be completely protected from paint over-spray and other contamination that may occur during manufacture or shipping. J. Grounding pads or connecting points shall be provided near the high voltage bushings for grounding each cable shield/neutral. K. Secondary Connecting Equipment: 1. The transformer secondary line and neutral bushings shall be electrically rated in accordance with section 2.01G. Page 4 of 8

5 2. The secondary neutral shall be grounded using a removable connection to the casing ground pad in accordance with IEEE C The connections shall be sized for the short circuit rating of the transformer. Short circuit durations are 2 seconds minimum for transformers 1000 kva and below. 3. Provisions shall be provided for removing the ground connection for testing purposes on the secondary neutral for either internal or external connections. L. Bushings for transformer secondary windings rated 208/120V: 1. The secondary voltage line bushing and neutral terminals shall be installed in accordance with IEEE C The neutral bushing shall be grounded externally or internally to the transformer ACCESSORIES AND MISCELLANEOUS A. All standard accessories shall be supplied. B. The transformers shall be provided with: Drain valves and threaded plugs A welded-on non gasket type magnetic liquid level indicator which will show proper level at 25 degrees C 2.04 INSULATING FLUID A. The transformer shall be shipped completely filled with insulating fluid. The insulating fluid to be used shall be a FR3. Certification must be provided stating that the oil is free of polychlorinated biphenyls (PCBs). B. The nameplate of the transformer, or other permanent stainless steel identification, shall specify the type of insulating fluid and that the insulating fluid is free of PCBs. The designation on the nameplate shall read CONTAINS NO PCB AT TIME OF MANUFACTURE or similar wording. Proposed similar wording shall be submitted to the Engineer for approval TANK GROUNDING Tank grounding provisions shall be provided in accordance with IEEE C , latest revision TRANSFORMER LABELING A. All labeling shall be in accordance with IEEE C , IEEE C , and IEE C B. Stenciled lettering on the tank shall mark bushings and fuse designations. Decal will not be allowed. C. The identification of voltage connections shall be shown on the instruction on the nameplate. Page 5 of 8

6 D. An instruction nameplate of stainless steel, or other approved corrosion-resistant material, shall be provided. This nameplate shall be securely attached to the top of the transformer by means of stainless steel or other non-corroding material screws, rivets, or other approved fasteners. The letters and numbers shall be stamped on the nameplate. E. The transformer will be marked on the nameplate or on a separate permanent stainless steel label, designating the brand name of the fluid, and stipulating that the fluid is biodegradable. F. Where removable current limiting fuses are used, the fuse holders shall include a warning baffle as a precaution against energized operation of the fuse-holder. PART 3 EXECUTION 3.01 TESTING, AND INSPECTION A. The applicable Design Tests in accordance with IEEE C shall be successfully performed for all designs. B. Each transformer shall have passed the following routine tests in accordance with IEEE C and C : 1. Resistance Measurements of all windings on the rated voltage connection. 2. Ratio tests. 3. Polarity and phase relation tests. 4. No-load losses and excitation current tests. 5. Load losses and impedance voltage. 6. Low frequency dielectric test. 7. Routine Impulse tests per IEEE C section The completed transformer shall be pressure tested in accordance with IEEE C section to insure that it is free from leaks and defects. 9. Oil dielectric tests from samples taken at the bottom of the units shall be performed per ASTM D1816 (0.04 inch gap) after assembly is complete and prior to shipment. 10. Oil test results for the supplied oil in accordance with ASTM D3487 Table 1 or ASTM 6871 Table 1 shall be provided for the latest fluids shipment prior to transformer filling. Page 6 of 8

7 C. A certified test report of all performed routine tests shall be supplied to the Engineer for each unit to be delivered under this specification. Test reports should reach the Engineer before the date of delivery of the units shipped, as this will be one of the bases of acceptance of the shipment. D. Accelerated aging tests on the paper insulation using shall be performed. E. The transformers minimum impedances. The Engineer may reject any units received with impedance values less than the listed values. F. The owner or its representatives may at any time perform audits, inspections, or observe the supplier s operations. The supplier shall cooperate and provide access to documentation, manufacturing, or testing. The owner s inspector shall be provided with full access to the facilities used for manufacturing. 1. These inspections do not relieve the supplier of their responsibilities for full compliance with all the requirements of these specifications. 2. The owner will notify the supplier of any situation where the work is not in accordance with the requirements of these specifications. 3. All costs incurred by the supplier as a result of rejection of material shall be considered incidental to the work. No separate payment will be made SHIPPING AND PACKAGING A. All units to be shipped in open rack type flatbed trailers. Closed van type trailers are unacceptable and will be rejected. Stacking of objects on top of each unit is not permitted. B. Units shall be mounted on a solid wooden pallet, or other approved pallet, for ease of removal with forklift truck. C. Units shall be protected during shipment so as to prevent damage to all exterior surfaces by the hold down devices. All parts of the transformer in contact with shipping hold-down devices should be protected to prevent chafing or other damage. Units showing damage to the paint finish are subject to rejection by the district and corrective action by the manufacturer. D. Freight on board (FOB) destination Any location within the city of San Francisco, CA DRAWINGS AND MANUALS A. Drawings and technical data on the proposed transformer to be manufactured shall be submitted to the Engineer for review and approval prior to manufacturing or shipping. B. These drawings shall include the following: 1. Detailed drawing of the unit showing final dimensions, clearances, and weight 2. Exterior mounted devices 3. Parts list including catalog numbers 4. Nameplate Page 7 of 8

8 5. Installation, Maintenance, and Operation Instructions 6. Recommended spare parts list 7. Standard 1 year warranty END OF SECTION Page 8 of 8