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Blackout traced to Ohio

WASHINGTON (AP) - 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.

Experts are working to understand why the local line disruptions, some of which occurred an hour before the blackout reached its peak, were not isolated, allowing a cascade of power system shutdowns stretching 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,'' said Gent in a telephone conference call.

Later, in a statement suggesting human failings for the events last Thursday, Gent said in the future ''system operators … will be extremely vigilant'' when local transmission problems arise.

Energy Secretary Spencer Abraham, who is co-chair of a U.S.-Canadian task force that will look into the cause of the blackout, said it's still too early to pinpoint a cause.

''We're not going to prejudge where the problem is,'' Abraham told reporters in Albany, N.Y., on Saturday where he met with the governors of New York and New Jersey to discuss the blackout. ''We're also not going to prematurely leap to conclusions.''

Abraham said the task force is putting together investigative teams that will include experts from the government's research laboratories as well as private resources, to find out what caused the power grid breakdown and recommend actions to prevent a repeat.

Gent did not identify specifically the three power line failures that have become the focus of the NERC investigation. But other council officials said they were among five reported transmission failures in the Cleveland area during a period of just over leading up to the blackout peak Thursday afternoon.

According to NERC, the first report came in at 3:06 p.m. EDT on Thursday and involved a 345-volt line that had ''tripped'' - or gone off line. 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 Corp., based in Akron, Ohio. The company has declined to comment on the investigation. ''Those reviews have not even come close to being completed and we're not going to speculate,'' FirstEnergy spokeswoman Kristen Baird said Saturday before Gent's announcement.

''It appears the train left the tracks in Ohio but we don't know who's responsible,'' said Alan Schriber, chairman of the Public Utilities Commission of Ohio.

Gent said he is confident the specific reason for the failures - and who is responsible - will be learned, but that it could take many weeks.

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.