What is a relay?

A relay is an electromagnetic switch. An actuating current passed in a coil operates one or more galvanically separated contacts. In fact it is a remote controlled switch capable of switching multiple circuits, either individually, simultaneously or in sequence.    

The most widely used type of relay is electromechanical relay. In electromechanical relays the switching element is a mecahncial contact, actuated by an electromagnet. This is the msot widely used type of relay design. The principal internal functions of the electromechanical relay are:

  1. Conversion of electrical current into  magnetic field
  2. Conversion of magnetic field into a mechanical force
  3. This Mechanical force operates the contacts
  4. Contacts switch and conduct electrical current
Applications of Relay

Typical applications of relays are as follows:
  • Laboratory instruments
  • Telecommunication systems
  • Domestic appliances
  • Traffic control
  • Control of motors & solenoids
  • Air conditioning & heating

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