A Brief Overview about Types and Applications of Relay Relay is a device with contacts that precisely opens and closes a switch as the result of an input signal (which can be voltage or current) applied to a coil. It is essential to understand that relays are used in the majority of electronic devices that uses electricity for their functioning. Structure and Operating Principle General purpose or solid state relay works on the principle of an electromagnetic attraction. It energizes the electromagnetic field which produces the temporary magnetic field when the circuit of the relay senses the fault current. This magnetic field moves the relay armature for opening and closing the connections. It is essential to understand that small power relay has only one contact and the high power relay has two contacts for opening the switch. Application for Relays Home Electrical Appliances Relays find a wide application in home electrical appliances such as refrigerators and washing machines. Industrial Machinery Relays are widely used in various industrial machines such as molding equipment, programmable controllers, industrial robots, and packing machinery. Scientific Equipment Relays are widely used in various constant temperature tanks. OA Devices These are widely used in different types of copy machines. Communication and Measurement Equipment Various types of relays are used in different measurement equipment. Automatic Vending Machines and Entertainment Equipment