A protective relay is an automatic device that detects abnormalities in an electrical circuit and closes its contacts. This action completes the circuit breaker 's trip coil circuit, causing the breaker to trip and disconnect the faulty section from the healthy circuit. Types of Protective Relays: Protective relays are categorized by their mechanism (electromagnetic, static, mechanical) and function. Electromechanical protective relays at a hydroelectric generating plant. In electrical engineering, a protective relay is a relay device. 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. A single-phase model of a simple power system is developed using the Power System Blockset. Circuit Breakers (CBs), as well as Voltage and Current.
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