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By Associated PressA system to isolate line failures should have stopped the problem before it spread. Next question to answer: Why didn't it?
WASHINGTON - 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 system was designed to isolate such problems and suggested 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.
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 said 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 leading up to the blackout peak Thursday afternoon.
According to NERC, the first report came in at 3:06 p.m. on Thursday and involved a 345-kilovolt 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, which 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 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 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.
Some key moments2 P.M. FirstEnergy Corp.'s Eastlake Unit 5, a 680-megawatt coal generation plant in Eastlake, Ohio, trips off. On a hot summer afternoon, "that wasn't a unique event in and of itself," says Ralph DiNicola, spokesman for Akron, Ohio-based FirstEnergy. "We had some transmission lines out of service and the Eastlake system tripped out of service, but we didn't have any outages related to those events."
3:06 P.M. FirstEnergy's Chamberlain-Harding power transmission line, a 345-kilovolt power line in northeastern Ohio, trips. The company hasn't reported a cause, but the outage put extra strain on FirstEnergy's Hanna-Juniper line, the next to go dark.
3:32 P.M. Extra power coursing through FirstEnergy's Hanna-Juniper 345-kilovolt line heats the wires, causing them to sag into a tree and trip.
3:41 P.M. An overload on First Energy's Star-South Canton 345-kilovolt line trips a breaker at the Star switching station, where FirstEnergy's grid interconnects with a neighboring grid owned by the American Electric Power Co. AEP's Star station is also in northeastern Ohio.
3:46 P.M. AEP's 345-kilovolt Tidd-Canton Control transmission line also trips where it interconnects with FirstEnergy's grid, at AEP's connection station in Canton, Ohio.
4:06 P.M. FirstEnergy's Sammis-Star 345-kilovolt line, also in northeast Ohio, trips, then reconnects.
4:08 P.M. Utilities in Canada and the eastern United States see wild power swings. "It was a hopscotch event, not a big cascading domino effect," says Sean O'Leary, chief executive of Genscape, a company that monitors electric transmissions.
4:09 P.M. The already lowered voltage coursing to customers of Cleveland Public Power, inside the city of Cleveland, plummets to zero. "It was like taking a light switch and turning it off," says Jim Majer, commissioner of Cleveland Public Power. "It was like a heart attack. It went straight down from 300 megawatts to zero."
4:10 P.M. The Campbell No. 3 coal-fired power plant near Grand Haven, Mich., trips off.
4:10 P.M. A 345-kilovolt line known as Hampton-Thetford, in Michigan's thumb region, trips.
4:10 P.M. A 345-kilovolt line known as Oneida-Majestic, in southeast Michigan, trips.
4:11 P.M. Orion Avon Lake Unit 9, a coal-fired power plant in Avon Lake, Ohio, trips.
4:11 P.M. A transmission line running along Lake Erie to the Davis-Besse nuclear plant near Toledo, Ohio, trips.
4:11 P.M. A transmission line in northwest Ohio connecting Midway, Lemoyne and Foster substations trips.
4:11 P.M. The Perry Unit 1 nuclear reactor in Perry, Ohio, shuts down after losing power.
4:11 P.M. The FitzPatrick nuclear reactor in Oswego, N.Y., shuts down after losing power.
4:12 P.M. The Bruce Nuclear station in Ontario, Canada, shuts down after losing power.
4:12 P.M. Rochester Gas & Electric's Ginna nuclear plant near Rochester, N.Y., shuts down after losing power.
4:12 P.M. Nine Mile Point nuclear reactor near Oswego, N.Y., shuts down after losing power.
4:15 P.M. FirstEnergy's Sammis-Star 345-kilovolt line, in northeast Ohio, trips and reconnects a second time.
4:16 P.M. Oyster Creek nuclear plant in Forked River, N.J., shuts down because of power fluctuations on the grid.
4:17 P.M. The Enrico Fermi Nuclear plant near Detroit shuts down after losing power.
4:17-4:21 P.M. Power transmission lines in Michigan trip.
4:25 P.M. Indian Point nuclear power plants 2 and 3 in Buchanan, N.Y., shut down after losing power.