Transformer failure leaves San Jose neighbourhood without power during heatwave

What happened

A broken transformer on PG&E's network cut power to about 340 people in the Almaden neighbourhood of San Jose at 8:34 pm on Saturday 15 August 2020, during a heatwave across the Bay Area. According to PG&E's website, the outage was caused by the broken transformer. Power was restored around 4 pm on Monday 17 August, after about 44 hours without power. Residents were without air conditioning overnight, and some stayed elsewhere.

One resident reported losing hundreds of dollars' worth of groceries. The outage came while the state grid was under strain. The city's mayor said PG&E had blamed the California Independent System Operator for the outage, and said the cause was PG&E's own failing system.

Contributing factors

The mayor said heat was a contributing factor, but that the fundamental reason was inadequate infrastructure that PG&E had failed to maintain and replace over many years. These are the mayor's views, not findings. No other contributing factors were reported.

Lessons learned

1. Replace or refurbish ageing distribution transformers on a planned schedule based on condition and load, rather than waiting for failure, particularly before heat-driven peak demand.
2. Maintain a plan for temporary generation or mobile transformers so that long restorations during extreme weather can be shortened.
3. Give affected customers prompt, accurate and consistent information about the cause of an outage and expected restoration times, especially when the outage coincides with wider grid shutoffs.

More lessons on maintenance, inspection and ageing assets, weather and external hazards, outages, backup supply and restoration, from every incident on the register.

Source

cbsnews.com