October 20th 2008 ARC Procedure

Monday October 20th 2008 06:20 EST through 06:55 EST the Midwest ISO invoked the ARC procedure for a combination of reasons; 675 MW of generation failed to start per plan, 450 MW of generation was unavailable due to boiler issues and began to ramp off line, and loss of ~800 MW of NSI from 06:00 – 06:30 EST. Up to 68 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.