[Best] Applications of Relay and Relay Function

The main function of Relay is that it acts as both ON and OFF switch at the same time. The main applications of Relay are switching, sensing, actuating, etc. In this article, you will find the best Relay Applications and the Relay Function. Relays are used from very small electronic circuits to very large high-voltage circuits for switching purposes, protection purposes, and sensing purposes. So read the full article to know more about the relay.

Relay Function

There are different types of switches used for different purposes. To ON or OFF those switches we need to push manually. But relay is a switch that does not require to push manually for ON or OFF. It is an electrically operated switch. If we take an example of the simplest and basic relay, then we will see that the main function of the relay is that it will act as an ON switch or allows current to flow through it when an electrical supply is applied and it will act as an OFF switch or does not allow the flow of current when the electrical supply is removed from it. You can see the basic relay concept in the below figure.

The most usable and conventional relay acts as both ON and OFF Switch together. That means these types of relay have two functions, one is normally ON and another is normally OFF. If you see in the below figure then you can easily understand the two functions of Relay.

As you see in the above figure when the supply is not given to the relay coil, the upper LED which is connected with the NC or Normally Closed will glow and the lower LED is OFF. But when the supply is given to the relay coil the lower LED will glow and the upper LED is OFF. So you may understand the relay working as both ON and OFF switch together. This was the function of a conventional relay or SPDT relay.

So the main functions of the relay are,

1.      Switching

2.      Sensing

3.      Indicating

Relay Applications

There are different types of relays which are used for different purposes. Relays are used in both electrical and electronic circuits.

Applications of Relay in Electrical Circuits

1. Relays are used in electrical circuits with the circuit breaker for protection purposes. Relay senses the fault and gives a signal to the circuit breaker, then the circuit breaker breaks the circuit. Most of the circuit breakers cannot work without a relay.

2. Relays are also used in some devices that are used in electrical circuits for protection purposes, and switching purposes such as Contactors, electrical switches, etc.

Applications of Relay in Electronic Circuits

There are huge applications of Relay in electronic circuits even more than electrical circuits which are given below,

1. In earlier days, the relay was used in telegraph lines.

2. In the electronic circuit, high-speed relays can be used for amplifying purposes because they can switch a high amount of current by taking a small amount of current.

3. In the electronic circuit, the relay is used with the microcontroller to drive a large load that cannot be driven directly with the microcontroller.

4. Relays are used in lighting dimmer circuits. And it is controlled by any IC or programming device.

5. Relays are used in motor control circuits.

6. Relay is also used in logical control circuits.

7. There is a huge application of Relay in PLC or Programmable Logic Controller.

8. The routing and signaling system in Railways uses the relay logic circuits. 

9. Relays are used in traffic light control systems. Here relays are used with the microcontroller and work as a driver.

10. There is a huge application of Relay in the home automation system.

Different Types of Relay Applications

Thermal Over Load Relay: They are used in Motor starters such as DOL Starter, Star Delta Starter, etc.

Mho Relay: They are used in Extra High Voltage and Ultra High Voltage transmission lines for protection purposes.

Polarized Relay: They were used in telephone lines in earlier days.

Solid State Relay: Their uses become increasing due to low loss and fast operation. They are used for the motor control circuit and many electronic circuits.

Impedance Relay: They are used in transmission lines to sense the fault current.

Read Also

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• Why Diode used in Solar Panel, Relay and Soldering Iron?
• Application, Advantages and Disadvantages of all types of Circuit Breaker
• Importance and Operation Sequence of Isolator, Circuit Breaker, Earthing Switch

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