69kV/13.6kV Substation Transformer

1. The Contractor shall design, manufacture and test one 69 kV delta to 13.6/7.85 kV wye, outdoor power transformer with primary (high voltage) and secondary (low voltage) bushings in accordance with all applicable industry standards including, but not limited to the latest revisions of the following: American National Standards Institute (ANSI) Institute of Electrical and Electronics Engineers (IEEE) National Electrical Manufacturers Association (NEMA) American Society for Testing and Materials (ASTM) National Electrical Safety Code (NESC) National Electrical Code (NEC) International Electrical Testing Association (NETA) American National Standards Institute (ANSI) 2. Transformer shall be three-phase oil-filled, two-winding, top connected, helical or disk core form construction type transformer with a high voltage de-energized tap changer and a low voltage automatic full-load tap changer. 3. The transformer will typically be operated in the neutral, de-energized tap position with transmission line nominal voltage of 69 kV and shall be designed to withstand five percent overvoltage under load and ten percent no-load overvoltage. 4. The equipment will be utilized in an unprotected outdoor environment with a ambient temperature range of -35C to +45C, an ice loading of 13 mm (radial), and a maximum wind speed of 90 miles per hour. The equipment will be installed at an altitude of approximately 375 meters (1232 feet) above sea level. 5. The transformer and ALL ancillary components shall be designed to have an acceptable loss of life of no more than 0.5 percent based on a normal insulation life assumption of 180,000 hours for an emergency overload of 140 percent for a time period of four hours, assuming preloading conditions of 70 percent of 65C top nameplate rating (28 MVA) and an average ambient of 30C. All transformer components shall be rated for this maximum overload condition. 6. The Contractor shall be responsible to coordinate and deliver the transformer F.O.B. to the foundation of each substation. Contractor shall set the transformer on the foundation to align with new bus arrangement. City Utilities requires Contractor to timely submit outline drawings such that the new foundation may be designed and installed before the date of delivery. Control conduit stub-up &/or stub-outs and ground lug locations shall be clearly indicated on the shop drawings. 7. Contractor’s transformer site-work installation shall include, but not limited to; transformer field assembly, transformer dress-out, field oil filling process, field testing (see section T.8.d) and documentation. Contractor shall furnish and deliver miscellaneous materials. Control cables and power wiring external to the new transformer that connect to owner’s remote equipment will be furnished and installed by City Utilities. City Utilities shall have the right to observe and inspect Contractor’s field site work. 8. All documentation and verbal discussions shall be English. 9. All materials bid and/or furnished must be new and unused, unless otherwise stated.