Protective relays and devices have been developed over 100 years ago to provide “lastline”of defense for the electrical systems. They are intended to quickly identify a fault and isolate it so the balance of the system continue to run under normal conditions. It functions as a watchdog by constantly surveying multiple system components including voltage, current, frequency, and phase angle. Its main purpose is to safeguard electrical equipment like transformers, generators, and transmission lines from damage due to. Relion protection and control relays for several application reduce complexity.