CITY COUNCIL AGENDA ITEM
ACTION REQUESTED:
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Approve the award of Cooperative Procurement 19-233, Transformer Remanufacturing and Tap Changer Board Replacement, to WESCO for an amount not to exceed $141,596
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DEPARTMENT: Electric Utility
SUBMITTED BY: Lucy Podlesny, Director
BOARD/COMMISSION REVIEW:
N/A
BACKGROUND:
The Electric Utility has 37 power transformers at its 16 electrical substations. While the input and output voltage of these transformers vary depending on the substation and the customer(s) that are being fed from the station, the purpose of these transformers is the same: to convert high voltage to a lower voltage that is more suitable for distribution to the Utility's customers.
The Utility performs monthly substation inspections and bi-annual oil analyses of its transformers in addition to specialized testing to reduce the likelihood of premature transformer failure. During a recent inspection, it was determined that there was a potential problem with one of the transformers at the Pebblewood substation.
Previously, the Electric Utility contracted with ABB, the transformer's manufacturer, to drain the oil from the load tap changer (LTC), a device that regulates the output voltage of the transformer and perform a visual and mechanical inspection. This analysis was completed in June and the final determination was that a barrier board, which ensures separation of the LTC and main tank oil, was leaking.
To ensure the reliability of this transformer, the barrier board must be replaced. The process to replace the barrier board includes draining the LTC and main tank oil, replacing the barrier board, processing the removed oil to remove contaminants and moisture introduced while draining the tank and finally filling and testing the transformer and LTC. If this barrier board is not replaced, it is very likely the transformer will fail due to the lowered levels of oil in the main transformer tank and the dirty LTC oil mixing with main tank...
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