Understand Relays: What is a Relay and How Does it Work?

What is a relay?

A relay is an electrically operated switch. Like any other type of switch, it can either break a connection, connect two points, or disconnect them. We use them to turn on and offloads electronics. Still, many different types of relays behave differently depending on the application. This article will look at some of these different types of relays and how they work!

What is a relay

Types of Relays

According to their use as well as the type of power, we require a relay. Organizing relays based on these criteria allows engineers and technicians to choose an appropriate relay for a given application.

Electromechanical switch

Electromechanical switches are an older type of switch that contains moving parts. It consists of a coil, armature bar, and contacts. An electrical current passing through the coil causes the armature bar to move, making or breaking connections in switches or circuits.

Solid-state switch

The solid-state switch is a modern version of the electromechanical relay. These look similar but do not contain moving parts like an electromechanical relay. The most common type of solid-state relays is known as thyristors or SCRs (silicon-controlled rectifiers).

Reed Switch

A reed switch is generally considered a compassionate type of relay that uses magnetic fields to activate switches inside the button itself.

Working principle:

An iron core encircles a control coil. As indicated, the power source provides to the electromagnet via a control switch and contacts to the load. The electromagnet energizes and thereby enhances the magnetic field when electricity flows through the control coil. As a result, the top contact arm is drawn to the lower fixed arm, closing the contacts and generating a power short circuit to the load. If the relay had already de-energized when the connections get completed, the contacts would travel in the other direction, resulting in an open circuit.

When the coil current gets off, a force returns the movable armature to its original position. The strength of this force will be nearly half that of the magnetic force. Two variables are primarily responsible for this force. They are the spring and gravity, respectively.


Relays are basic switches that can control electrically or manually. An electromagnet and a set of contacts make up a relay. The electromagnet is to carry out the switching mechanism. Many more principles govern its operation and, however, differ in terms of their applicability. Most gadgets use them.


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Deepak Kumar Thakur

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