Reliability of protection and control equipment in the context of compensation for power supply interruptions

The paper reports results from a recent study of the Norwegian fault statistics for protection and control (P&C) equipment in relation to quality of supply. Today, incorrect operation of protection equipment at the distribution level is seldom registered in the fault statistics. Therefore, the results presented in this paper mostly consider P&C equipment at the levels 33-420 kV. Results are given for number of faults, fault causes as well as contribution to energy not supplied and customers´ interruption costs. These results will be an important basis for the further specification of requirements related to protection and the choice of equipment and functionality