MIDDLETON, Wis. - The first signs of trouble in the Northeast's electrical supply showed up near Lansing, Mich., seconds before spreading to the rest of the region, a company that monitors power grids said Friday.

SoftSwitching Technologies executives say their data shows the cause of the nation's largest blackout could be rooted in that state.

"We think a disturbance occurred in Michigan," said David Trungale, the firm's vice president of sales. "That disturbance led to a generator failure. In power dynamics, it's always a chain reaction."

He said he didn't know where the generator was or why it may have shut down.

A company monitor in the Lansing area was the first to detect a deep voltage sag two seconds after 4:09 p.m. EDT Thursday, Trungale said.

Within seconds, monitors around the Northeast began to detect frequency decay in power grids in Ohio, which spread to Ontario, Canada; New York; Vermont and Pennsylvania.

The company has more than 1,000 power monitors nationwide, with most in the Northeast and Midwest, Trungale said. He declined to say where the Lansing monitor was located, citing customer privacy.

The company is sharing its data with the U.S. Department of Energy, Trungale said.

DOE spokeswoman Jeanne Palotto said the agency is collecting data from many sources and hasn't reached any conclusions yet.

Nationally, investigators have said the power disruptions likely began in the Midwest, but they have yet to pinpoint the cause.

Michigan Public Service Commission spokeswoman Judy Palnau said the commission planned to launch an investigation into outages in that state Monday. She declined to comment on SoftSwitching's findings, saying only the commission will look at all factors.

Dennis Ray, executive director of the University of Wisconsin-Madison's Power Systems Engineering Research Center, said it could take six to nine months to find out what caused Thursday's massive blackout that knocked out service in parts of eight states and Canada.

But SoftSwitching president Deepak Divan said the odds were good the cause of the outage lies in Michigan.

"We measured it (the voltage sag) in Michigan but nowhere else within 200 monitors in the blackout area," Divan said.

Michigan's power grid automatically isolated itself before collapsing completely, Divan said. For some reason, the Ohio grid apparently did not, which caused the frequency decay to spread, he said.

The complex, interconnected nature of the eastern United States' power grid increases the risk of failure, said UW-Madison electrical engineering professor Ian Dobson. One failure can weaken the system and leave it vulnerable to more breakdowns.

"Electrons do not respect state boundaries ... they follow their own laws," Dobson said.

Divan, a former UW-Madison electrical engineering professor, said he started SoftSwitching in 1995 to help industry and utilities protect themselves from power disruptions.

The company introduced a monitor last year that utilities and industrial customers can buy for $200 to $300, Trungale said.

The monitors, a little smaller than a shoe box, plug into a regular electric outlet and transmit information about power fluctuations through phone lines to SoftSwitching's online data base.

SoftSwitching monitors the readings and then notifies its customers of power fluctuations within minutes. Most utilities haven't invested in technology to monitor their grids because it's too expensive, Divan said.

Some of SoftSwitching's customers include General Motors and hospitals in the Northeast as well as Milwaukee-based We Energies, he said.

Margaret Stanfield, a We Energies spokeswoman, declined to comment on any of the utility's vendors or equipment Friday.

On the Net:

SoftSwitching: http://www.igrid.com