[Explained] Main Differences Between Relay and Contactor


Relay and Contactor Difference


The main difference between Relay and Contactor is, Relay is used in low power, low current carrying circuits for switching and controlling but Contactor is used in high power, high current carrying circuits for switching purpose. The other important differences between Contactor and Relay are given below.


Basically, Contactor and Relay both are the electrically operated switch. To automatic control the electrical circuit we use Contactor and Relay. Contactor and Relay both are works in the same principle. Both of them have electromagnet inside them. The simple working principle of Contactor and Relay is that when the electromagnet is energized by an external power supply, they change their contact mechanisms, such as NO(Normally Open) to NC(Normally Closed) or NC to NO.



Here you can see the symbolic difference between the relay and Contactor.


Relay and Contactor Symbol, Relay Symbol, Contactor Symbol




Relay VS Contactor



(1) First of all, the actual difference between the Contactor and Relay is, Relay is a low power device whereas Contactor is High Power Device.


(2) For up to 10 to 15A circuits Relays are used, whereas more than 15A to 12500A circuits Contactors are used.


(3) Relays are smaller in size than Contactor whereas the Contactors are bigger in size than Relays. Contactors are heavier than the Relays.


(4) Basically, Contactors are designed to operate at Normally Open(NO), on the other hand, Relays are designed to operate at Normally Open(NO) as well as Normally Closed(NC). But nowadays, some Contaauxiliarys auxiliary NC contacts. It is an important difference between Contactor and Relay.


(5) The main use of a Contactor is switching, but Relays are used for switching purpose as well as controlling purpose. But the modern Contactors also has auxiliary NC, NO contacts for using controlling purpose. I mean to say modern Contactors also used for switching as well as controlling.


(6) Relays are comparatively low-cost devices than Contactors whereas the Contactors are high-cost devices than Relays.


(7) A Relay cannot be used in Power circuit for higher voltage, it only used in control circuit but Contactors are designed to use in power circuit for higher voltage.


(8) Contractors are mainly designed for Three Phase applications whereas Relays are mainly designed for single phase applications.


(9) Generally, Contactors are rated for up to 1000V but Relays are rated for up to 250V.





(10) As Contractors are designed for high current applications so they have some safety features such as spring-loaded contacts. Generally, spring-loaded contacts are used to prevent internal short circuit of the Contactor when it carries high current.

Contactor has another safety feature that is ARC suppression. As they carrying high current, so there is a chance of producing ARC.
Relays have not any safety features like spring contacts, ARC suppression system. So it is a very important difference between Relay and Contactor.


(11) Generally, Contactors come with embedded Thermal Over Load relays which gives Overload and Short Circuit protection. Relay has not overload protection facility.


 (12) In modern days, many smart electrical, as well as electronic devices, use Relays, Contactor mainly used for ON/OFF the Motors, and other high power devices such as large lighting systems, etc.


(13) Switching time of Relays much faster than Contactors that is why Relays are also used as sensing Device.


(14) Contactors consume more power as they have large Electromagnet than Relays, on the other hand, Relay consumes low power as they have small electromagnets.


(15) Another important difference between the Contactor and Relay is, as the switching speed of the Relays are very much faster than Contactors so they can be operated with electronic signals but Contactors are cannot be used with electronic signals.





Here you can see the Different types of Relay,



Types of Relay- SPST, SPDT, DPDT, DPST



What should I Use Relay or Contactor?



As I already told, For high power application Contactor is best. So for high power application, you should use Contactor. If you need very fast switching speed then you must use Relay. For low power application always, use Relay because it can save your money. It is not economical to use Contactor for low power application.






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[Explained] Main Differences Between Relay and Contactor [Explained] Main Differences Between Relay and Contactor Reviewed by ETechnoG on 21:28 Rating: 5
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