PG&E tweaking power-line shutoff trigger with help from aerial inspections

Pacific Gas and Electric have received many customer complaints about automatic switches that shut off power because they have too much of a hair trigger. But ongoing adjustments are being made as the high wind, wildfire season descends upon us.

On Tuesday, a PG&E helicopter flew power lines in Sonoma County that pass through one of the utility's highest fire-risk areas. Way up high on main power lines, they are placed in heavily wooded, high wind areas. The pilot and observer look for branches, trees or even the remains of roosting wild birds that can short power lines out.

But, PG&E now knows that the switches have too much of a hair trigger, causing warranted shut offs. So, the hair triggers are being adjusted to be less hairy, so to speak.

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"Over time, we're continuing to refine them, to make them better so that we're balancing between that customer interruption and the safety we have," said Joe Horak, PG&E's Sonoma Division superintendent.

Installing more properly adjusted, automatic quick shutoff switches can, and does reduce the number and length of outages. "We have seen a reduction in potential ignitions by 60% from this time compared to last year," said PG&E spokesperson Deanna Contreras.

The switches also reduce the size of outages by bypassing areas that do not need to be cut off. With smaller outage areas, air and ground inspectors can more quickly assure any equipment needing repair  is fixed and the line reenergized. Tweaking the triggers is helping find the sweet spot between unnecessary outages and wildfires.

Without helicopters, each fault could take two to three times as much time to get the line back in service. The more they inspect, the more efficient they get. 

But what about days when the weather is too foggy or too bad to fly? 

"We're gonna put someone under that line and their gonna hike to it. Whether that takes us an hour, whether it takes us five hours, we gonna do it because we're not gonna re-energize that line until we know it's safe to do so," said Horak. Once the lines are cleared, power control can remotely re-activate the power line. "Almost instantaneously," said Horak.

The fact is, we're now in or at least entering the high-wind season; the Diablo winds, the Santa Ana winds. 

The reality is, as those winds come up, these things are gonna trip. That's the acid test. But, if they do trip and they prevent a fire, then it's a success.