How Electrical Relay Works?

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.

Juan is a Design & Tech Blogger with strong interest in digital art, human computer interaction, enterprise system and system automation.

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