Relay and Coordination

Traditionally, utilities have defined reliability as the ratio of the time power was available in a given period divided by the total time in the period. Nationally, reliability figures are typically in excess of 99.98%. While this is commendable, it is no longer an accurate indication of the quality of service the utility is delivering to its customers.

Today's businesses can come to a screeching halt with the occurrence of a single momentary outage. In the past most of these instantaneous operations went unnoticed. But today, microprocessors see any power anomaly. A one second outage will do nothing to impact system reliability, but could be devastating to a single customer.

The utility can track system performance by a variety of methods. Tracking of momentary interruptions by reading and recording counter values on OCBs will prove a more valuable tool than the classic calculation of minutes of customer interruption.

The way the system is designed and its response to problems should reflect the need for "computer grade" power. In some cases it may even make sense to decrease reliability to increase quality.