Relay protection is a complex of devices designed for quick, automatic (in case of damage) detection and separation of damaged elements of this electric power system from the power system in emergency situations in order to ensure the normal operation of the entire system. Actions of means of relay protection are organized according to the principle of continuous assessment of the technical state of individual controlled elements of electrical power systems. Relay protection (RZ) continuously monitors the state of all elements of the electric power system and responds to the occurrence of damage and abnormal conditions. When damage occurs, the relay should detect the damaged area and disconnect it from the EPS, acting on special circuit breakers designed to open the damage currents (short circuit).
Relay protection is the main type of electrical automation, without which the normal operation of power systems is impossible.