Introduction to Relay

Relay is a switch which opens or closes the circuit electronically.

Relays are electromagnetic devices.

When the fault is detected,this Relay device is designed to trip the circuit breaker.

Relay is a best device to control the circuits by a low – power signal.

Relay control a circuit by opening and closing  contacts in another circuit.

When the relay is not energized and it have Normally open contact then there is an open contact.Similarly when the relay have Normally closed contact then there is a closed contact. 

When the Relay is energized or voltage is applied then the relay can be used to switch the lower voltage to higher voltage.

Relays were first used in long-distance telegraph circuits as signal repeaters: they refresh the signal coming in from one circuit by transmitting it on another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations.