Safeguards Save the Day As Lights Go Out in West
Brief shutdown of power prevented burnout of grid
BOSTON — A SUDDEN loss of power in 1 million Western households early Wednesday points up the vulnerability - and survivability - of America's intricate electric system.
While people groped in the dark for candles and flashlights in California, Washington, and several other states, technicians scrambled to track down the problem and route power around a failed electric transmission line.
It could have been much worse.
``The system has this protection built into it to prevent the kind of disaster that hit the Northeast in 1965,'' says Greg Pruett, a spokesman for Pacific Gas and Electric (PG&E), the utility whose power line failed. Within 17 minutes after the line went down, according to Mr. Pruett, PG&E was able to find alternate routes for the massive flow of electricity, which was being shipped from Southern California up to Oregon and Washington in a complex grid that supplies the entire West Coast.
Disruptions were felt in eight states, including Montana and Utah. In Arizona, a few traffic lights blinked on and off as power fluctuated, says a spokesman for Arizona Public Service Company.
Several things happened quickly after the transmission line failed at 12:26 a.m. The sudden break caused a dangerous buildup of power south of the failure point and an equally dangerous dearth of power to the north.
The bad line was between Fresno and Tracy in California's Central Valley. The Diablo Canyon nuclear generating plant near San Luis Obispo, pumping hundreds of megawatts into the system, was shut down by automatic sensors.
``If this had not happened,'' says Sgt. Bill Souza of the San Luis Obispo County Sheriff's Office, ``it would be like pumping thousands of gallons of water into a broken pipe - only this would have burned up a lot of the system.''
Meanwhile, safeguards in power companies up and down the West Coast began to shut down whole grids, cutting off power and lights for 1 million customers. This process absorbed the strains on the larger grid and prevented the entire system from collapsing.
``I was called at 12:30 a.m.'' [four minutes after the line failure in the California Central Valley], says Rick Searing, an engineer for Portland General Electric in Oregon.
He explains what happened there: ``We have under-frequency relays that detect such problems and start to shut down whole areas. The system runs normally at 60 cycles, and when the cycles drop, our protection system kicks in.''
By 3 a.m., he says, ``we had power back into all households and businesses. It took at least 100 of us to do it, all of whom were called right away.'' Similar rapid emergency service was performed up and down the coast.
The quick response yesterday in the West was in sharp contrast the famous blackout in the Northeast in 1965.
Just after 5 p.m. on Nov. 9, 1965, a power surge in an Ontario power plant tripped a series of circuit breakers and within 15 minutes, up to 33 million people lost power in New York, New England, and parts of Canada. People were stranded in trains and elevators, and planes were diverted to distant airports. It took ten hours to restore power.
The North American Electric Reliability Council was set up after the 1965 outage to find ways to prevent such a disaster again. The council's president warned as recently as January 1991 that the power distribution system in North America had to be watched carefully for ``possible deterioration.'' He pointed to more fully loaded transmission lines than desirable, among other things.