Jan 22 U.S. federal energy regulators on
Wednesday preliminarily determined several companies had
violated various reliability standards, causing a blackout in
2011 that left about 2.7 million homes and businesses in the
Pacific Southwest without power.
The staff at the Office of Enforcement at the U.S. Federal
Energy Regulatory Commission (FERC) did not include any
penalties in its so-called notice of alleged violations.
The outages affected parts of Arizona, southern California,
and Baja California in Mexico. Some customers were without power
for up to 12 hours, FERC said.
The companies alleged to have violated the reliability
standards are Pinnacle West Capital Corp's Arizona
Public Service utility, the California Independent System
Operator, Imperial Irrigation District, Edison International's
Southern California Edison, Western Area Power
Administration and the Western Electricity Coordinating Council
The outage started with the loss of Arizona Public Service's
Hassayampa-North Gila 500-kilovolt power line that transports
electricity from generators in Arizona through the Imperial
Irrigation District service area in Southern California and into
the San Diego area.
But FERC and the North American Electric Reliability Corp
(NERC), which oversees the nation's reliability rules, said in a
report in April 2012 the loss of one big power line was not the
sole cause of the widespread outage.
The loss of the Hassayampa-North Gila line caused the power
flows to move onto lower voltage power lines, creating overloads
that eventually resulted in the blackout, FERC and NERC said in
the 2012 report.
During the event, FERC and NERC said in the report that the
WECC reliability coordinator issued no directives and the
transmission operators took only "limited mitigating actions."