A protective relay operates by continuously monitoring electrical parameters, detecting abnormalities, making decisions, and triggering circuit breakers to isolate faulty sections. This process helps protect equipment, maintain power system stability, and ensure safety for. A protective relay is an intelligent device that senses abnormal electrical conditions, such as overcurrent, under-voltage, or frequency deviations. They are intended to quickly identify a fault and isolate it so the balance of the system continue to run under normal conditions. The selection and applications of. Relion protection and control relays for several application reduce complexity.