PG&E Pinpoints Failing Regulator As Groveland Outage Cause

Groveland, CA — The widespread multi-day power outages in the Groveland area was part of the Enhanced Power Line Safety settings, which cuts off power when there is something threatening the system which could cause a wildfire.

More specifically, PG&E has determined it was a “failing regulator” that spurred the disturbance.

Tuolumne County District Four Supervisor Kathleen Haff reports that she has requested PG&E to come to the July 18 supervisors meeting in light of growing community concerns. She is also requesting that PG&E connect to the microgrid already in place in downtown Groveland for (PSPS) planned power outages, anytime the power goes out in that area (including unplanned outages).

PG&E is tentatively scheduled to speak at 1:30 pm during the July 18 board meeting.

Supervisor Haff has also provided an email that she received from PG&E’s Local Government Affairs representative, Nathan Alonzo, about the incident. You can read it below:

“We understand the frustration of our customers. Serving your hometowns is a privilege and we know that on the holiday weekend, there were an unacceptable number of outages that took too long to restore.

We have identified and repaired the root cause of the prolonged outages over the July 1-3 period on the electric distribution circuit serving the community in the Groveland area. After three outages with no obvious fault condition, we identified that a failing regulator was the cause of the outages. A regulator is a piece of equipment that maintains voltage levels on an electric distribution system. Contributing causes included the heat, which led to peak loads far in excess of any seen in the last three years. That in turn further stressed the equipment and exacerbated a complicated/challenged restoration.

This is a rare case where a piece of equipment that is failing is difficult to identify immediately. The Enhanced Powerline Safety Settings recognized the voltage fluctuations caused by the regulator and shut off power, preventing a potential significant mechanical failure of the regulator that could have caused a fire ignition.

However, we could not identify the regulator as the cause of the outages until there was visible damage to that equipment. We have replaced three regulators on that circuit, and we do not expect any additional outages. We will have extra staffing in place this coming weekend due to the heat.”