September 18, 2007 Arc Event

Tuesday September 18, 2007 from 15:30 EST through 20:15 EST the Midwest ISO invoked the ARC procedure due to 1,100 MW Net Scheduled Interchange obligation change over a ten minute period created by TLR curtailments. Up to 85% of the available ARC operating reserves were utilized during this period to correct the imbalance. There were no ARS events during the procedure.