Ohio line failure likely cause of big blackout

Alarm systems that might have alerted engineers to the failed lines were broken, according to FirstEnergy Corp., the Akron, Ohio-based utility that officials said owned at least two of the three lines.

It was not immediately clear whether that impeded efforts to isolate the local line disruptions, some of which occurred an hour before power system shutdowns cascaded Thursday from Michigan to New York City and into Canada.

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"We are fairly certain at this time that the disturbance started in Ohio," Michehl Gent, head of the North American Electric Reliability Council, said in a statement. "We are now trying to determine why the situation was not brought under control after three transmission lines went out of service."

Gent said the transmission system was designed to isolate such problems and suggested that human error might have been involved in not containing the situation.

"The system has been designed and rules have been created to prevent this escalation and cascading. It should have stopped," Gent said in a telephone conference call.

FirstEnergy, which officials said owns four of the first five lines that failed, said a system that is supposed to flash a red warning on computer monitors at the company's control centre was not operational when the lines began failing Thursday afternoon.

FirstEnergy was aware the alarm system was broken, said company spokesman Ralph DiNicola. A functioning backup alarm at the Midwest Independent System Operator, a non-profit power pool that oversees the region's electrical grid, was in place, DiNicola said.

At the Midwest ISO, spokeswoman Mary Lynn Webster said she did not know when workers noticed the FirstEnergy lines were disabled and what, if anything, they did about it.

Webster said the pool copes with "thousands of alarms every minute," and that the failed lines weren't in areas most prone to problems.

A failure in the monitoring system could be devastating because it prevents operators from isolating failures before they spread, said Thomas Stuart, a professor of electrical engineering at the University of Toledo.

Energy Secretary Spencer Abraham, co-chair of a US-Canadian task force that will look into the cause of the blackout, said the group is putting together investigative teams that will include experts from the government's research laboratories as well as private resources. In addition to determining the cause, the task force will recommend actions to prevent a repeat.