Protective relays are power system protection devices that monitor current, voltage, frequency, impedance, or differential quantities and command circuit breakers when faults or abnormal conditions occur. Engineering use: Relays are used on feeders, transformers, buses, motors, generators, and transmission lines to protect equipment and improve system. A protective relay is an intelligent electrical device designed to detect faults in power systems and initiate corrective actions such as tripping a circuit breaker. Types of Protective Relays: Protective relays are categorized by their mechanism (electromagnetic, static, mechanical) and function. Selectivity is a mandatory requirement for all protection, but the importance of it depends on the application. The primary protection scheme ensures fast and selective clearing of any circuit fault within the boundaries of the circuit element, that the. However, due to their very long life span, tens of thousands of these "silent sentinels" are still protecting transmission lines and electrical apparatus all over the world. Important transmission lines and generators have cubicles dedicated to protection, with many individual electromechanical.
