According to the Institute of Electrical and Electronic Engineers (IEEE C37. 100-1992), a protective relay is: “A relay whose function is to detect defective lines or apparatus or other power system conditions of an abnormal or dangerous nature and to initiate appropriate control. In electrical engineering, a protective relay is a relay device designed to trip a circuit breaker when a fault is detected. It functions as a watchdog by constantly surveying multiple system components including voltage, current, frequency, and phase angle. It. Protective relaying aims to stop that chain reaction before it starts, detecting problems instantly, cutting off the affected section, and keeping the rest of the system stable and safe.