The US/Canada Power Outage Task Force reported on September 12. It compiled the following timeline, focusing on events that occurred on August 14 on transmission facilities of 230 kV and greater, and at large power plants.
It does not explain the linkages between the events, or why the blackout happened, but acknowledges that its next task is to address the causal relationships among these events. Determining them will require intensive analysis of the thousands of transmission line events that occurred on the 138 kV system and on lower voltage lines over the several hours before and during the grid's collapse and the hundreds of events related to power plant interactions with the grid, as well as the many things that happened before noon (most of the events that appear to have contributed to the blackout occurred between noon and 16:13), including reactive power and voltage problems and flow patterns across several states that may be implicated: together with any actions taken, or not taken, by system operators prior to or during the outage.
Event times were derived from the "time stamp" that accompanied each data record, and recorded to the nearest second, and sometimes to a fraction of a second. A source of inaccuracy that is still to be reconciled, mainly by cross-checking, stems from the fact that time stamps from different areas are not necessarily synchronised - because the recording computers became backlogged, or the clocks they used had not been calibrated to the national time standard.
For the full published sequence of events see Modern Power Systems, September 2003 pp 3-5 or go to the NERC website, www.nerc.com.
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