A joint U.S.-Canadian task force investigating this nation's biggest blackout released yesterday its first timeline of events that showed unusual voltage drops and power plants in southern Ohio and Michigan shutting down hours in advance of the outage.
The number of incidents in FirstEnergy Corp.'s territory prior to the Aug. 14 outage that deprived power to 50 million people from Ohio to New York and into Canada likely will raise questions about whether the parent of Toledo Edison knew whether major problems were coming, and what it could have done to prevent them.
Task force investigators placed no blame in yesterday's report, but federal officials said the final report will explain what happened and why, as well as how to prevent a recurrence.
Separately, FirstEnergy, the utility which is the focus of much of the investigation into the blackout, said it has discovered that its transmission lines were heavily loaded, apparently from sales that sent power produced elsewhere across its grid to customers outside of its territory.
The company's transmission wires carried 20 percent more power than a typical peak summer usage day, but it did not have peak demands from its customers, a spokesman said. The only explanation, the spokesman said, was power being sent through its system for outside users and produced by outside generators.
Whether the high volumes contributed to the blackout is uncertain.
The timeline shows in chilling detail how the blackout across eight states and southeast Canada unfolded four hours before the 4:10 p.m. collapse of the transmission grid. The outage took out 61,800 megawatts, enough power for 49.4 million homes, but the reason for every incident is not provided in the report.
The timeline “is only a step. It's far from a finished product,” U.S. Energy Secretary Spencer Abraham said in a conference call with media from the United States and Canada.
Assembling the timeline was a challenge, in part because precise times for some events are unclear. The report notes “time stamps'' recording events, such as transmission lines disconnecting, were not always accurate because computers recording the information became backlogged with data, and clocks were not synchronized with national time standards.
The 14-page report did not address events prior to noon Aug. 14 but said investigators will do so to determine if any were relevant.
Investigators have noted that FirstEnergy's Eastlake Unit 5 plant near Cleveland shut down at 1:31 p.m. Aug. 14, likely contributing to instability on its grid.
But the report notes two other plants - Conesville Unit 5, a 375-megawatt plant in central Ohio and owned by American Electric Power, and Greenwood Unit 1, a 785-megawatt plant north of Detroit and owned by DTE Energy - stopped producing at 12:05 p.m. and 1:14 p.m., respectively, causing power flow patterns to shift. Conesville returned to service about 40 minutes later.
The report identifies several previously unknown events that may have contributed to the blackout, bolstering FirstEnergy's longstanding posture that many events, some outside its territory, contributed to the blackout.
For example, a key 345-kilovolt transmission line in southwestern Ohio was exposed to a brush fire at 2:02 p.m. and disconnected from the system, thereby limiting the electric pathway from southwestern Ohio to northern Ohio.
A voltage collapse in the system caused transmission lines and power plants to shut themselves down, the report said.
The report noted a potential loss of “reactive power” as a contributor to the voltage loss. Reactive power is a technical term for the special type of electricity that cannot travel far but is needed to keep voltage high enough to propel megawatts across transmissions lines and is needed to run electric motors.
Without such power, the electrical system doesn't work right, and turns itself off. “That's how you save the system,” said Dr. Thomas Stuart, a professor of electrical engineering at the University of Toledo.
From 3:05 p.m. to 3:41 p.m. Aug. 14, the report said, two transmission lines in northern Ohio owned by FirstEnergy and one line co-owned by FirstEnergy and American Electric Power disconnected. One line sagged into a tree and short-circuited, but reasons for the other disconnects are unknown.
With those lines out, remaining lines connecting eastern Ohio and northern Ohio became overloaded and caused a voltage drop. The report said industrial customers using about 600 megawatts of power in northern Ohio shut down before the major blackout because their electric motors turned off from a lack of voltage.
After several transmission line failures and a Lansing area power plant shutdown, power flows from Indiana into Michigan and Ohio became heavy as the states tried to pull power from elsewhere to meet demand, and voltage dropped, forcing more grid failures.
By 4:10 p.m., 20 generators producing 2,174 megawatts shut off in several power plants along Lake Erie in northern Ohio, presumably including Toledo Edison's Bay Shore plant, and more transmission lines were cutting off.
As Michigan and northern Ohio scrambled to obtain power from anywhere, the situation worsened. When transmission lines along the southern Lake Erie shore shut down, power on that path reversed direction and began flowing in a giant loop counterclockwise from Pennsylvania to New York to Ontario and into Michigan. During the next 1 minute and 19 seconds, a cascade of failures spread into Canada and east into New York and Connecticut. By 4:13 p.m., the collapse was complete.
FirstEnergy has acknowledged an alarm that should have warned of some failures didn't work, and its staff told callers from neighboring utilities and an oversight group that its computers were not working properly. But the company has maintained that only multiple problems across an area broader than its system could have resulted in the blackout.