Unified four characteristics of relay protection

It begins by outlining the four key characteristics of relay protection: selectivity, sensitivity, speedability, and reliability. Protective relays and devices have been developed over 100 years ago to provide “last line” of defense for the electrical systems. They are intended to quickly identify a fault and isolate it so the balance of the system continue to run under normal conditions. Static relays can achieve such a high performance that the departures from the. (1) Selectivity: refers to that when the Electrical fault occurs, the relay protection device acts and only removes the fault element. Types of Protective Relays: Protective relays are categorized by their mechanism (electromagnetic, static, mechanical) and function. A protective relaying scheme should have certain important qualities. [pdf]