Sensitivity is the ability to detect small faults, and selectivity is the ability to discriminate faults within the relay's zone of protection. Based on simple examples of the generator-transformer unit protection from symmetrical short circuits, it was shown that the sensitivity factor is not a sufficiently objective measure of sensitivity of the. The relay protection sensitivity is one of the determined factors in the power system, however, it is often overlooked in current distribution network (DN) planning. For example, unselective protection operation during a medium voltage network fault will cause an outage for an unnecessarily large number of consumers. While this is bad, It's not a. What are the four requirements for a protective relay to function properly? Sensitivity, Selectivity, Speed, Reliability What are the four requirements for a protective relay to function properly? A measure of the degree of certainty that the relay system will perform correctly What is relay. Dependability refers to a relay operating when expected to, while security means a relay does not operate when not expected to. Stability Test: Verifies that the protection is stable & does not operate over through-faults (external faults).
