UPDATE 4-San Diego power problems ease as key line returns
(Updates with return of key Southwest Powerlink, grid manager still on guard)
LOS ANGELES, Oct 24 (Reuters) - California wildfires created an electricity "island" of San Diego County on Wednesday but a major blackout was averted when a key power transmission line to Arizona resumed operation in the afternoon, San Diego Gas & Electric Co. said.
The Southwest Powerlink is one of two major transmission corridors that connect San Diego County to the U.S. West power grid. It had been out of service since Sunday when wildfires approached it.
The other major link in the north part of the SDG&E service territory ceased operation about the same time the Southwest Powerlink restarted, said Rachel Laing, spokeswoman for SDG&E. It was back in operation by early Wednesday evening.
"For the moment, it looks like crisis averted," Laing said.
SDG&E and the manager of the state power grid were still asking consumers to conserve power because the Southwest Powerlink is not yet up to full electricity flow rates and wildfires remained unpredictable and could imperil power lines again.
"The winds are cooperating a little better at least with regard with the fires that are burning near our transmission lines," said Stephanie McCorkle of the California Independent System Operator, which manages the grid that handled 80 percent of California's electricity.
Four days of wildfires have caused the largest evacuation in California's history.
California had the most transmission lines out of service on Wednesday than ever before, said McCorkle.
"This is unheard of, to lose this many transmission lines," said McCorkle. "But it is obviously a historic disaster we are dealing with."
Power outages were down in both the SDG&E area on Wednesday at about 20,000 customers, down from 33,000 on Tuesday. And the Southern California Edison area to the north had only about 2,000 powerless customers.
SDG&E gets about half of its power from outside its service area.
Every power plant within the SDG&E area was called upon on Wednesday, even those that are 50 years old and only run during the highest demand, said Michael Niggli, chief operating officer for SDG&E.
SDG&E was being helped on Wednesday by importing about 200 megawatts on a 230-kilovolt link to Mexico that was also under threat of going off line due to fire. It is called the Talega-Escondido line.
The Cal ISO will officially extend a "transmission emergency" for a fourth day on Thursday, McCorkle said, largely because of the diminished flow on the Southwest Powerlink.
"The system is still strained," she said. "We are in a precarious situation although it has improved."
