Proposed statistical performance measures for microprocessor-based transmission-line protective relays. I. Explanation of the statistics

The paper presents practical calculations and novel techniques for collecting performance data from protective relays. The methods are focused on, but not limited to, microprocessor-based transmission line relaying systems. Standard definitions are presented for availability, dependability, security, hardware MTBF, relaying MTBF, repair time, and other measures of interest for specific relay types. The paper explains the novel concept of exposures, the key to a standardized security measure. With these standard measures, relay users will be able to compile the first consistent industry-wide data base for relay performance assessment.