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How Electrical Relay Works?

# Technology

The are various type of relay available in the market such as power relays, solid-state relays, PCB relays, sensor relays, socket relays, time delay relay and many more. Relay is a simple electrical switching mechanism which use electromagnet to control and complete a circuit by using a low-power signal. In this post, we will take readers to learn how a relay works. More after the jump.


Relay was originally invented by Joseph Henry, an American Scientist in 1835. Joseph invents a basic relay system to improve his very own version of electrical telegraph.

A relay is a simple yet important electrical part which can be found easily in any electrical device and the most basic example is on off switching system. You may find a relay is your tv remote control and so on which is used to control electrical output.

How it Works?

Relays are such a simple device which consist four important part. A simple relays consist coil with soft iron core, moveable armature, spring and set of electrical contacts.

How relay works?

Refer figure, When the switch is on, electromagnet generates a magnetic field to activate the armature to complete the circuit. When switch is off, no magnetic field will be generated and in this case, the circuit is not complete.