Search Baja California

Friday, September 9, 2011

NEWS - Power Outage Caused by Human Error


Power has been restored to most of the nearly 5 million customers in the Western U.S. and Mexico who were affected by a massive power outage Thursday afternoon that has been attributable to human error.

The Arizona utility issued a press release saying that it believes the outage was caused by an employee who was working at a substation near the North Gila - Hassayampa 500 kV transmission line located near Yuma, Ariz. The utility says approximately 56,000 customers lost service throughout Yuma, Somerton, San Luis and Gadsden.

Operating and protection protocols typically would have isolated the resulting outage to the Yuma area, which says an investigation into why this did not occur is currently underway.

The Federal Energy Regulatory Commission (FERC) and the North American Electric Reliability Corp. (NERC) have also announced a joint inquiry into the power outage. The agencies report that as of 2:15 a.m. PDT today, all but 200 MW of the initial 4,300 MW lost had been restored.

FERC and NERC will coordinate with the Department of Energy and other federal agencies, the California Independent System Operator (CAISO), the Western Electricity Coordinating Council, California and Arizona state regulators and the companies involved to monitor the situation. The inquiry will focus on causes of the outages.

San Diego Gas & Electric (SDG&E) had restored power to its 1.4 million customers affected by the outage as of 3:25 a.m. local time, the utility stated in a press release, which also cited Arizona as the originating point of the outage.

About 3.5 million people in Baja California, Mexico, were also without power, Reuters reports.

The loss of a key connection with the San Onofre Nuclear Generating Station and other factors resulted in the most widespread power outage in the company's history, according to SDG&E.

The station, which is operated by Southern California Edison (SCE), shut down on Thursday and remained without power on Friday, Reuters reports.

The utility coordinated its restoration efforts with the CAISO, which issued a transmission emergency after the outage caused all of SDG&E and a small portion of SCE customers to lose power. CAISO cited a tripped 500 kV high-voltage line from Arizona to California as the cause of the disruption.

Although the Sept. 8 outage, apparently caused by human error, was just a tenth the size of the 2003 blackout that left about 50 million people without power in the eastern United States and Canada, it will surely rank as one of the biggest blackouts in recent history - certainly one of the biggest caused by human error.

SDG&E and the California ISO, which operates the power grid for much of the state, said they would focus on maintaining and ensuring the integrity of the local power system for the next
few days before determining the sequence of events that led to the outage and establishing practices and procedures to ensure that outages such as the Sept. 8 event are not repeated.

"There appears to be two failures here -- one is human failure and the other is a system failure. Both of those will be addressed," said Damon Gross, a spokesman for Pinnacle West
Capital's (PNW.N) Arizona utility Arizona Public Service.

As reported by AP and Reuters.