A. These specifications cover the electrical and mechanical features of three-phase, 60 hertz, 65 degrees C rise, mineral oil filled, pad-mounted, compartmental type distribution transformers with separable insulated high voltage connectors. Transformers shall be furnished completely assembled and filled with oil. Bidder shall certify that transformer oil contains no PCB contaminants. B. Transformers shall comply with the latest revision of ANSI C57.12.26, except where it conflicts with the specific requirements of these specifications. C. All transformers manufactured under this specification shall be tested for no load (85 degrees C) and total (85 degrees C) losses, percent impedance (85 degrees C) and exiting current (100% voltage), and subject to a full wave voltage impulse. Actual loss data shall be prepared in accordance with the attached form. D. Each bidder shall supply verification that the design has passed short circuit criteria per ANSI C57.12.00 - 1980 and ANSI C57.12.90 - 1980. E. All ANSI standards contained in the specifications refer to the latest revision. F. Transformer shall be three-phase, pad-mounted distribution type, 60 hertz, liquid immersed, self--cooled, and suitable for outdoor service. G. Transformer shall be rated 24,940 Delta - 480 GrdY/277 volts, 60 hertz, 125 KV BIL. The transformer shall have an average winding rise not exceeding 65 degrees Centigrade. KVA ratings shall be as specified in the proposal section at the end of this schedule. H. Transformer shall have six primary bushing wells suitable for use with 200-ampere loadbreak bushing inserts. Primary connections shall be arranged for loop-feed. Transformer shall have three insulated secondary bushings and one grounded secondary neutral bushing. Secondary bushings shall have spade type terminals with NEMA standard ten (10) hole spacing. There shall be a parking stand for each primary bushing. I. Transformer shall be delta-wye connected and shall have a five-legged core or other means of avoiding tank heating due to third harmonics. Transformer shall be furnished with a parking stand for each primary bushing. J. Transformer shall be equipped with three primary liquid-immersed fault-sensing expulsion type loadbreak fuses in series with internal current limiting fuses, with provisions for hotstick removal. Transformer shall also be equipped with a pressure-vacuum gauge and a pressure relief device. The tank will be constructed to withstand a minimum of 12 psig with rupture. K. Transformer shall be dead-front primary type with separate high- and low-voltage compartments. The high-voltage compartment shall be fastened from inside the low-voltage compartment, and the low-voltage compartment shall have provision for padlocking. The unit shall be suitable for installation without a fence or other protective enclosure. L. Transformer shall have a complete nameplate inside and outside the low-voltage compartment, external tap changer handle, provision for tank grounding, and provision for bolting to a foundation pad. Transformer shall conform to the requirements of ANSI Standard C57.12.22 except where the standards conflict with the requirements of these specifications. The unit shall be regular in the outline with no projection other than cooling fans, lifting lugs, and door handle.
