Michehl Gent, president of the North American Electric Reliability Council said that though the cause remains unknown, but indications so far point to a downed power line east of Cleveland, Ohio, on the "Lake Erie loop" -- a series of transmission lines around the lake -- as the source of the outage.
Later Friday, Gent told CNN it appears that the first known problem was the loss of a power line in Cleveland, Ohio, at 3:06 p.m. Thursday. The loss of the power line could be an early link in a chain of events that led to the blackout, he said.
The blackout began spreading in New England, the upper Midwest and parts of Canada just after 4:10 p.m., taking down 21 power plants in the next three minutes, according to Genscape, which monitors power transmissions in the United States.
Gent said power on the northern side of the lake was flowing from west to east just before the incident, and "as it unfolded, the power reversed itself" and nearly doubled.
"There was a big swing back and forth on the north of the lake," he said. "The whole loop had this oscillating power phenomenon that ... was essentially a nine-second event."
From that initial incident, he said, the blackout cascaded off the loop and spread before the electrical system "did what it was supposed to do" and stopped it.
NERC does not consider terrorism or cyberterrorism possible causes.
"Physical terrorism is fairly easy to rule out," he said. "There's no evidence of a blowup, or somebody breaking in."
As for cyberterrorism, "it's virtually impossible to get in without leaving some tracks," he said. "They can cover their tracks as far as who they are but they cannot cover their tracks about where they've been."
As for what the "nine-second event" might have been, Gent said, the investigation would uncover it.
"There are two possibilities," he said. "Either the rules that we have are inadequate and need to be changed to accommodate this unknown event, or somebody wasn't following the rules."
Later Friday, Gent told CNN it appears that the first known problem was the loss of a power line in Cleveland, Ohio, at 3:06 p.m. Thursday. The loss of the power line could be an early link in a chain of events that led to the blackout, he said.
The blackout began spreading in New England, the upper Midwest and parts of Canada just after 4:10 p.m., taking down 21 power plants in the next three minutes, according to Genscape, which monitors power transmissions in the United States.
Gent said power on the northern side of the lake was flowing from west to east just before the incident, and "as it unfolded, the power reversed itself" and nearly doubled.
"There was a big swing back and forth on the north of the lake," he said. "The whole loop had this oscillating power phenomenon that ... was essentially a nine-second event."
From that initial incident, he said, the blackout cascaded off the loop and spread before the electrical system "did what it was supposed to do" and stopped it.
NERC does not consider terrorism or cyberterrorism possible causes.
"Physical terrorism is fairly easy to rule out," he said. "There's no evidence of a blowup, or somebody breaking in."
As for cyberterrorism, "it's virtually impossible to get in without leaving some tracks," he said. "They can cover their tracks as far as who they are but they cannot cover their tracks about where they've been."
As for what the "nine-second event" might have been, Gent said, the investigation would uncover it.
"There are two possibilities," he said. "Either the rules that we have are inadequate and need to be changed to accommodate this unknown event, or somebody wasn't following the rules."
