What is a Magnetic Contactor and its working principle?

What is a Magnetic Contactor?

Magnetic contactors are the same as the electrical relays found in many electric motors. Magnetic contactors are used in electric motors to balance changes in the motor’s frequency or state. This is called turning the motor from ON to OFF.

Magnetic contactors are widely used in industry. The big commercial industry relies heavily on this device. Thanks to it, heavy loads like large-capacity motors can be easily controlled.

Working Principle

Basically, a magnetic touch works at the identical principle as a relay. The actuators are similar, this tool makes use of a coil, which creates a magnetic discipline withinside the electrified coil.

When an electric powered modern flows right into a magnetic discipline coil positioned withinside the middle of the coil center. This creates a magnetic discipline wherein the magnetic discipline forces triumph over the spring pressure and in this situation the metallic center actions downwards (ON).

Two units of contactors will alternate the working conditions. They are

• The normally closed (NC) contactor will open the contact point circuit and • The normally open contactor (NO) will open the contact circuit, connect the circuit of the contact point when there is no current flowing to the coil, all contactor magnetic fields.

The basic elements of magnetic contactors are as follows.

  1. Iron Core The iron core is divided into two parts:

  2. Fixed Core Coil is energized, it becomes an electromagnet.

  3. Moving Core The coil is energized, the magnetic contactor closes and the moving core is pushed into the fixed core.

  4. Coil The coil is energized to draw the main contact, and the auxiliary contact uses the power of that coil to operate.

  5. Contact

There are mainly two types available.

• Main Contact

• Auxiliary Contact

Main Contact

In an electrical circuit, the main contact, sometimes known as the “main contact,” is used to link an electrical system to a load.

Auxiliary Contact

As the secondary switching, the auxiliary contact is utilized in conjunction with the “auxiliary contact control circuit.” When the contactor is idle, it is generally open, and when it is active, it is normally closed.

Auxiliary connections are permitted to pass through minor currents that are utilized to indicate the state of the main contacts. In other words, it serves as a gateway to the control system.

Advantages of Magnetic Contactors

  1. Provides high safety for operators
  2. Provide ease of control
  3. Economical compared to manual controls


  1. The coil may burn if there is no magnetic field.

  2. When exposed to moisture, ageing of components promotes corrosion of materials. Applications of Magnetic Contactors

The following are some of the applications of magnetic contactors.

• Magnetic Motor Starter

• Lighting Control Contactor