What Is A Contactor, And How Does It Work?

by Anne Zavala

An electrical contactor is commonly known as a switching gadget. It is broadly utilized for the switching of engines, capacitors, and lights. In capacitors, it is used for correcting the power factor. As the name demonstrates, like a traditional on and off switch, contactors are used to make or break contact. The main contrast between the switches and contactors is that the contactors have an electromagnet that holds the contacts when it is powered while switches don’t have it. Contactors come in a wide range. The main types are DC and AC contactors. They vary in their design and a little in the way they operate. The most common are 24V DC coil contactor. In this article, we look at the basics of contactors.

How do contactors work?

Contactors work almost the same way as relays with the exemption that contactors carry more current than the latter. For this reason, regular relays can’t be legitimately utilized in circuits where the current surpasses 20 amperes. In such conditions, contactors are the best option. Also, contactors come in a wide range. The different types of contactors are categorized based on their ratings and forms. Contactors with the highest rating reach a limit of 12500A. Note that contactors are not designed to protect a short circuit. However, they can make and break contact when they are powered.

How contactors work is quite simple. What happens is that when the electromagnetic coil is powered at any time, it causes an electromagnetic field to form. This electromagnetic field draws in the metallic bar, which is known as armature towards the hole in the empty round and hollow magnet.

In contactors with split electromagnets, the movable portion of the electromagnet is pulled in towards the fixed electromagnet. This activity shuts the contacts. The contacts stay shut as long as the electromagnet stays powered. At the point when the coil is no longer energized, the moving contact is pushed back by the spring to its original position. In simple terms, contactors are designed in such a way that they open and close very quickly. Moving contacts may ricochet as it quickly makes contacts with the fixed contacts. Bifurcated contacts are utilized in some contactors to keep them from bouncing.

The contribution to the contactor loop might be AC or DC or even all-inclusive. They are both accessible in different voltage ranges beginning from 12Vac/12Vdc to 690Vac. There are universal loops. These are those that can work on AC just as DC voltages. Then the contractor is operating, and it uses up a small amount of power. However, there are energy-efficient contactors that are designed to use up the least amount of power during their operation.


Contactors with AC loops have coils that shade. Another element of the contactor is that it may chatter each time the rotating current crosses zero. Also, note that the shading coils defer demagnetization of the attractive center hence avoiding the chattering. In DC contactors, shading is not an issue because the motion that is created in the loops is consistent. 

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