White Rock transformer fails; utility outlines three-pronged reliability plan
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Summary
A 61-year-old substation transformer in White Rock failed on Aug. 8. Department staff outlined three emergency options — tie to LANL with voltage regulators, deploy a mobile substation, or buy/refurbish a replacement transformer — and estimated costs and timelines for each.
A transformer at the White Rock substation suffered an internal failure Aug. 8, disrupting service and prompting Department of Public Utilities staff to present a multi-part reliability plan to the Board of Public Utilities on Sept. 3.
The transformer, from 1964, showed signs of high heat at failure and is out of service; crews restored some power by about 6 a.m. the day of the failure. DPU staff said dissolved-gas and oil testing are pending to help identify the exact failure mode. Dennis (DPU staff member) told the board the substation is electrically isolated and described three emergency and recovery options.
Why this matters: White Rock is served by only the substation’s two transformers; if the second transformer fails the community risks extended outages. The board heard options intended to limit outage duration and to provide a longer-term, upsized replacement aligned with the utility’s electrification planning.
The utility’s three response options
- Tie to Los Alamos National Laboratory (LANL) lines with voltage regulators: DPU staff said LANL has agreed in principle to work with the county to tie the systems, adding voltage regulators to step the LANL nominal 13,200 volts down to the county’s nominal 12,470 volts (planned operating level ~7,200 volts per phase after regulators). Staff estimated regulators would take about four weeks to arrive from suppliers; the LANL tie work had a preliminary cost estimate of about $75,000 and regulators about $70,000. Staff said the regulators and associated construction could be used later for other distribution upgrades.
- Deploy a mobile substation: DPU staff said a mobile unit from a neighboring utility (PNM) could be used under a mutual aid arrangement but that deploying a mobile substation typically takes a full day to set up and requires space and security for the equipment. Staff reported active conversations with PNM about mutual aid availability.
- Purchase or refurbish a replacement transformer: Staff said new transformers from some manufacturers have multi-year lead times; refurbished transformers were presented as a practical option with shorter delivery and acceptable warranties. Estimates presented during the meeting put replacement/refurbishment and supporting site work in the mid-hundreds of thousands of dollars; combined cost for replacement transformer plus foundation and connection work was discussed at roughly $750,000 (ballpark) and up to about $1 million when including regulators and other tie work. Staff said an upsized transformer (7.5 MVA and above, potentially larger) would better match the system’s future needs.
Technical and safety details
DPU staff said the transformer that failed showed localized overheating and that oil testing is expected to provide further diagnostic information (including checking for historical PCB contamination and dissolved gases such as acetylene). Staff noted the transformer has an older on‑tank tap changer and that some components would require rebuilding if a unit were refurbished.
Board questions and next steps
Board members pressed staff on timing, risks of deferring maintenance, options for rebuild versus replacement, and whether other transformers in the system posed similar risks. Staff said the other substation transformer is newer but does have a minor oil leak staff intends to repair; the system otherwise relies on the LANL tie for additional redundancy in town. Staff said they will pursue the LANL tie and procurement/refurbishment options in parallel, request on‑call engineering support for foundation and layout design, continue oil testing, and return to the board with updates. Staff described the LANL tie as the near-term priority (regulators and construction), with the transformer procurement discussion ongoing.
Staff emphasized minimizing long outages while avoiding a rushed procurement that would deliver equipment unsuited to future load growth. The board asked staff to continue work and to provide further cost and schedule detail at follow-up meetings. No formal board vote was taken on procurement or contract awards during the Sept. 3 meeting.
Ending: DPU staff said they would pursue the LANL tie and continue procurement work on the transformer while awaiting oil-test results; the board requested further updates and expected staff to return with formal recommendations when firm bids and schedules are available.
