What are Protective Relays, or Protection Relays? Protective relays are used in industrial power generation and supply systems to open and isolate branch circuits in the case of excessive current. In the United States, the National Electric Code (NEC) exists to guide electricians in the proper installation of electrical equipment and defines the specific requirements for circuit protection. The SCPD may be a fused switch or a circuit breaker. 52 provides the maximum sizes or settings for overcurrent devices protecting the motor branch circuit. They include both. Long term cost reduction (TCO) for trainings and maintenance by reduce variety of relays A fast and selective arc fault mitigation for air-insulated LV & MV switchgear and Relion protection and control relays and sensor technology protect staff and plant facilities for many years. Branch circuit protection is a mandatory safety system designed to prevent the electrical wiring within a structure from overheating, which is the leading cause of electrical fires.