1. Electromagnetic relay is an important component in electric bells, telephones and automatic control circuit devices. Its essence is a switch controlled by an electromagnet, and it plays a role similar to a switch in the circuit: 1. Use low voltage and weak current to control high voltage , Strong current; 2. Realize remote control and automatic control.

Second, the use of Electromagnetic relay can control the working circuit of high voltage and strong current with the control circuit of low voltage and weak current, and can realize remote control and production automation. Electromagnetic relays are widely used in automatic control (such as control circuits in refrigerators, automobiles, elevators, machine tools) and communications.