[Best] Applications of Relay and Relay Function

The main function of Relay is that it acts as both ON, 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 smaller electronic circuits to very large high voltage circuits for switching purpose, protection purpose, sensing purpose. So read the full article to know more about the relay.

Relay Function

There are different types of switch used for different purposes. To ON or OFF those switches we need to push manually. But relay is a switch which 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 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 act as both ON, OFF Switch together. That means these types of relay has 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 connected with the NC or Normally Closed will glow and 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 electronics circuits.

Applications of Relay in Electrical Circuits

1. Relays are used in electrical circuit with the circuit breaker for protection purpose. Relay sense the fault and give a signal to the circuit breaker, then the circuit breaker breaks the circuit. Most of the circuit breaker cannot work without a relay.

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

Applications of Relay in Electronic Circuits

There are huge applications of Relay in the electronic circuit 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, the high-speed relays can be used for amplifying purpose because they can switch the high amount of current takes a small amount of current.

3. In the electronic circuit, the relay is used with microcontroller to drive a large load which 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 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 use the relay logic circuits. 

9. Relays are used in traffic light control system. Here relays are used with the microcontroller and worked 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 Starter such as DOL Starter, Star Delta Starter, etc.

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

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

• Main Differences Between Relay and Contactor
• 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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