A failure to contain problems with three transmission lines in northern Ohio just south of Cleveland was the likely trigger of the nation's biggest power blackout, a leading investigator said Saturday.
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.
"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 center 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 nonprofit 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 (news - web sites), co-chair of a U.S.-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.
The task force hopes to complete an initial report within a month, the Canadian co-chairman said Saturday. "We want to move as quickly as possible," said Canada's Natural Resources Minister Herb Dhaliwal, a former an electric company official.
Dhaliwal spoke Friday with Abraham and planned to meet him Wednesday in Detroit to talk about the panel's work.
Gent did not identify specifically the three power line failures that became the focus of the NERC investigation. But other council officials said they were among five reported transmission failures in the Cleveland area leading up to the blackout peak Thursday afternoon.
According to NERC, the first report came in at 3:06 p.m. EDT Thursday and involved a 345-volt line that had "tripped" — or gone offline. That was followed by reports on other lines failing at 3:32 p.m., 3:41 p.m., 3:46 p.m. and 4:06 p.m.
Two minutes later, according to the NERC summary, "power swings (were) noted in Canada and the U.S." and three minutes after that power disruptions hit across eight states.
The transmission system in northern Ohio is operated by FirstEnergy.
Among the things yet to be determined is the relationship between lines tripping in Ohio and the unusual power swings that were observed in lines leaving Michigan and going into Canada and then back again, according to investigators.
There are more than 10,000 pages of data, including automatically generated logs on power flows over transmission lines, that need to be closely examined, said Gent.
Complicating the matter, he said, is that at the time of the power breakdown "events were coming in so fast and furious that (some reports) ... weren't even being logged in a timely way."
Nonetheless, Gent said he is convinced that no data was lost and whatever was not recorded will be recovered.
"We will get to the bottom of this," he said.
Contributing to this story were AP writers Andrew Welsh-Huggins in Columbus, Ohio, Ryan Lenz in Indianapolis and Jim Krane in New York.
On the Net:
North American Electric Reliability Council: www.nerc.com