Specifications_For_The_Repair_of_Substation_Transformer_AC_21.pdf
PDF 52 KB Posted
- Solicitation number
- IFB197195
- Issued by
- Santa Clara County, California
About this file
This is a specifications document for the repair and refurbishment of a substation transformer issued by the City of Palo Alto Utilities in California. The project involves the complete replacement of a TLH-21 on-load tap changer (OLTC) on an Allis Chalmers 15 MVA, 60KV-12470/7200V substation transformer originally installed in 1967. The transformer, identified as AC-21 at Adobe Creek, is experiencing mechanical failures in the OLTC that prevent proper tap changing, though the core and coil remain electrically sound. The scope of work requires the contractor to provide all labor, equipment, and materials for draining approximately 4,348 gallons of oil from the main tank into a contractor-provided tanker for reuse and 760 gallons from the OLTC tank into City-provided containers for disposal. Additional work includes replacing the OLTC with a certified remanufactured component, resealing all barrier boards and pass-through studs to prevent oil migration, replacing LTC tank gaskets, removing and replacing the 60KV SMD fuse holder, replacing all six radiator valves and gaskets, and pressure testing the main tank with gasket replacement as needed.
The contractor shall perform comprehensive diagnostic testing before and after the repair work, including power factor testing on bushings and windings, TTR (turns ratio) testing on all OLTC positions, excitation testing, winding resistance measurement, SFRA (sweep frequency response analysis), and DGA (dissolved gas analysis) with oil quality testing including moisture content, dielectric breakdown, and power factor measurements at 100°C for both the main tank and OLTC. The City will be responsible for de-energizing, disconnecting, isolating, and grounding the transformer to establish a safe work area, as well as disposing of any oil not intended for reuse. The project objectives are to restore full mechanical functionality and dielectric reliability of the transformer system, prevent further degradation, and extend the operational service life of this critical distribution asset.
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| Adobe_Creek_Transformer-21;_15_MVA_LTC_Replacement_&_Radiator_Flange_Repair_Regasket_(Addendum_#1_Revision).pdf | ||
| Adobe_Creek_XF_21-5.jpg | JPG image | |
| Adobe_Creek_XF_21-4.jpg | JPG image | |
| Adobe_Creek_XF_21-3.jpg | JPG image | |
| Adobe_Creek_XF_21-2.jpg | JPG image | |
| Adobe_Creek_XF_21-1.jpg | JPG image | |
| 32_63-306-935-001.pdf | ||
| 31_63-306-932-405.pdf | ||
| Adobe_Creek_Transformer-21;_15_MVA_LTC_Replacement_&_Radiator_Flange_Repair_Regasket.pdf | ||
| Performance_Bond.docx | DOCX document | |
| Bid_Bond_Form.docx | DOCX document | |
| Payment_Bond.docx | DOCX document | |
| Specifications_For_The_Repair_of_Substation_Transformer_AC_21_(2).pdf | ||
| Construction_Contract,_General_Conditions,_and_Change_Orders.pdf | ||
| Bid_Form_For_AC_21_LTC_Repair.docx | DOCX document |
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Text version
Specifications for repair of Substation transformer AC 21
Replace the on-load tap changer (OLTC) on the Allis Chalmers 15MVA, 60KV-12470/7200V substation transformer. The OLTC is a TLH-21 from 1967. The unit is experiencing mechanical problems preventing the OLTC from changing positions. The transformer is energized and does not show signs of core and coil electrical malfunction. There is evidence of minor oil migration between the OLTC cabinet and the Main tank. There are two radiator valves leaking.
The contractor shall provide all labor, equipment and materials required to:
• Complete testing of the transformer prior to commencing any work
• Drain TLH-21 LTC tank into city provided containers for disposal. (760 gal)
• Drain main tank (4348 gal) into contractor provided tanker. Oil to be re-used.
• Replace the TLH-21 LTC with a certified re-manufactured component
• Re-seal barrier board and all pass-through studs to stop oil migration between LTC and Main tank
• Replace LTC tank door and hand hold gaskets
• Remove and replace the 60KV SMD fuse holder to accommodate removal of the radiators.
• Replace valves and gaskets on all six radiators
• Pressure test main tank and replace gaskets or seals disturbed during work.
• Process Main tank oil and vacuum fill transformer
• Fill LTC tank with new oil (760 gal)
• Complete testing of the transformer after completion of the work
The City will be responsible for de-energizing, disconnecting, isolating and grounding the transformer as required to establish a safe work area. The city will dispose of any transformer oil not to be re-used.
Preliminary tests of transformer condition.
• Power Factor the primary bushings
• Power Factor the primary and secondary windings
• TTR all positions of the OLTC (as found ONLY on the NLTC)
• Excitation
• Winding resistance
• DGA and oil quality testing includes moisture content, dielectric breakdown, and power factor @ 100°C (main tank and OLTC)
Post work tests to be performed:
• Power Factor testing on the bushings
• Power Factor testing on the windings
• TTR - all positions
• Excitation
• Winding resistance
• SFRA
• DGA and oil quality testing includes moisture content, dielectric breakdown, and power factor @ 100°C (main tank and LTC)
File details come from the government source that posted it. Updated .