August 28, 2008 ARC event

Saturday August 23rd 2008 19:55 EST through 20:35 EST the Midwest ISO invoked the ARC procedure due to a 2,300 MW Net Schedule Interchange obligation change over a 30 minute period created by schedule changes and TLR curtailments. Up to 80 percent of the available ARC operating reserves were utilized during this period to assist in correcting the imbalance. There were no ARS events initiated during the event.