Reliability Amid Heat Wave, Equipment Challenges

At 10 p.m. on a September evening, 800,000 pounds of steel carefully traverses across the 91 freeway and into the Inland Empire onboard a highly specialized transport rig. Weight-wise, the load is equivalent to 10 Tyrannosaurus rexes or three full-grown blue whales.

In this case, it is a massive transformer, escorted by three pilot vehicles and six California Highway Patrol cars, navigating numerous SoCal streets on its journey to replace a piece of Southern California Edison substation equipment that had failed near Ontario. The meticulously mapped route takes six hours to complete, and the 250-foot load is so large it could only move overnight.

SCE works with local agencies to transport a 217-ton transformer and replace a failed piece of equipment in the Ontario area.

"Getting the transformer here took cooperation and coordination with government agencies, local municipalities, public works and the Arizona Department of Transportation, which is where the trailer needed to transport the transformer came from," said Bryce Reeves, SCE Supply Chain advisor. "Big, big coordination on everyone's behalf."

The effort is necessary after an unexpected failure of one of SCE's three transformers that helps provide power to around 150,000 people in Ontario, Eastvale and surrounding cities. The malfunction happened in early September during one of the hottest weeks in the past 12 years, meaning air conditioners were blasting and electricity demand was high. One more glitch to either of the two remaining transformers would mean grid operators may need to deenergize customers.

SCE quickly coordinated with surrounding city and county officials to relay the need for energy conservation - a callthat was answered by customers - while grid operators took on the intricate work of rerouting power between circuits.

"The problem during heat waves is that you can't use all the normal ways of transferring system loading because everything's already so heavily loaded that you're just moving one problem to another location," said John Battenschlag, SCE Irvine Grid Control Center senior manager. "But there are some ways to move small pockets of load and lessen the problem."

While grid operators continued the delicate dance of balancing loads, local community partners posted on social media and reached out to residents asking for help. Customers enrolled in Demand Response programs made a difference, preventing the electrical equipment from becoming overloaded.

"It was incredibly helpful. We saw about 20 to 24 megawatts of load reduction thanks to customers," Battenschlag said.

With critical help from customers, the system made it through an intense heat wave despite the loss of equipment without needing to deenergize nearby communities.

Even before the system was in the clear, planning for a replacement transformer had started and a unit was soon being prepped to make its way from Hawthorne to Ontario to be installed.

At its final destination, crews jacked the replacement 217-ton transformer off the trailer and slid it onto the foundation. It is welded into place so it doesn't moves in case of an earthquake. After that, it goes through several rounds of testing before being connected to the grid.

"This is keeping the power on, as we like to say," Reeves said.

For more information on SCE's Demand Response programs, visit sce.com/resdrp.