A relay is a electrical switch which is used to open or close a circuit with electromechanical relay or electronically. A relay is a simple electromechanical switch made up of an electromagnet and a set of contacts. Relays are used where it is necessary to control a circuit by a separate low-power signal, or where several circuits must be controlled by one signal. It is generally used to switch lower current. Relay is electric device used to control high power to when turn on or off with using low power its uses a magnet made by solenoid it creates temporary magnetic field that attracts high switch.
There are two types of relay are,
Electromechanical Relays :
In electromechanical relays , contacts are opened or closed by a magnetic force.
Solid State Relays:
It control power circuits with no moving parts, instead using a semiconductor device to perform switching. With solid-state relays (SSR), there is no contacts and switching is totally electronic.