Top 7 Difference Between Relay And Contactor

Top 7 Difference Between Contactor And Relay:

Relay and contactor are functionally doing same duty, but the major difference between relay and contactor is that, contactor can carry huge amount of current but relay can carry only less amount of current from 0.1 A to 20 A. In this, we are going to see the 7 difference between relay and contactors.

What is Contactor:

Contactor is an electromagnetic switch, which can be operated by giving external power supply. The current carrying capacity of the contactor’s contact tips are high and having ability to break large amount of fault current (around several kA). Since they are coming with the arc chute which is used to quenching the electrical arc during opening condition.

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What is relay:

The designing and working principle are same as a contactor, but they are designed to carry a small amount of current. Since they seem very small.

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Difference Between Contactor And Relay

Common terms Between Contactor And Relay:

Contactors and relays are doing the duty of breaking (NO) and opening (NC) of the circuit. Both are having electromagnetic coils; the coil voltage depends on your source.  Sometime the contactor come with additional auxiliary contacts that may be either NO or NC. These auxiliary contacts get activated along with the main contacts. Switching is achieved by energization and de-energization of the contactor coils.

How to Choose Contactor and Relays:

When selecting between the two, some very general rules you can follow to help

When to Use a Relay:

  • 10A or less current
  • Coil Voltage Up to 250VAC and DC

When to Use a Contactor:

  • 9A or more current
  • Up to 1000VAC
  • 1 or 3 phase

Contactors are also chosen upon the ampere ratings of the load and require an additional supply (either AC or DC depending upon the type of contactor we use) for excitation. Finally, they are used for power switching and are usually open.

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Difference Between Contactor and Relay

S.No Contactor Relay
1 Electromagntic switch can carry huge amount of current Maximum 12,000A A electromagnetic switch can carry less amount of current Max. 20A
2 Arc chute must be present for Suppressing electric arc Arc chute will not be present
3 Bigger Size Smaller size
4 Mainly used for Switching power circuits such as Transformer, Induction motor starters, Capacitor bank etc. Mainly used in control and automation circuits, protection circuits and for switching small electronic circuits.
5 less number of NO and NC contact can be taken More number of contacts can be taken
6 Occupy less Space occupy More space
7 High Cost Less Cost

Video Explanation Difference Between Contactor and Relay



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