Disturbances by Cause
Reliability Performance Gap Index

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System Protection misoperations emerged as a key reliability concern in 2008. NERC will be launching an initiative to help address these issues in 2009.

About this Metric

This index is designed to measure how far the system is from expected performance under contingencies (dynamic conditions).  The RPG is defined as number of disturbance events in Categories 2 through 5 for a given period.  It measures the change in system ability to cope with pre-studied contingencies and unforeseen disturbances.  Ultimately, RPG indicates the most important measure of reliability standard and enforcement program effectiveness:  the number of events declining toward zero.