Discuss the details of magnetic contact


Many of us have heard the name of magnetic conductor in one way or another. Today we will learn more about magnetic communicators. Magnetic conductors are an interesting subject.

It’s a little complicated for many of us. In this article I will try to discuss in simple language. You should have a clear idea about the magnetic communicators.

What is a magnetic contactor?

A magnetic contactor is an electromagnetic driven switch. It is often used to control motors in many large automation industries. Its function and reel function are very similar. Then the question may be friends, if there is any one.

But no, relays are usually used at low power voltages and magnetic contactors are used at high power. When we create small projects in electronics, we see in many cases that we are using relays. It is used in motor control automation in many large industries.

So we can say that a magnetic contactor is a load conductor that is used to turn a power electric motor or load on and off. 

The structure of the magnetic contactor?

Its structure is very simple. Magnetic contactors consist of the following.

  • Main contact: It basically does the work of load off on by switching the power. It has 3 input and 3 output terminals. The input terminals are represented by L1, L2 and L3 and the output terminals by T1, T2, and T3.
  •  Auxiliary contact: This contact is usually used for the control circuit. This load is created in the circuit of automation mode or protection. It has two types of terminals. 1) Normally Open (NO) 2) Normally Close (NC)
  •  Power supply coil: This coil generates electromagnetic. When power is supplied to it, it becomes energized and turns into a magnet and brings the main contacts from normally open to normally close condition. The two terminals of the coil are denoted by A1 and A2. It energizes the solenoid. It comes in different power supply ranges (24VDC, 24VAC, 110VAC, 240VAC, 415VAC)
  •   Auxiliary block: Auxiliary block is used to connect auxiliary. Additional auxiliary open and normally closed terminals can be created using this auxiliary.

    Discussion of Normally Close and Normally Open Conductor

    These contacts are auxiliary contacts. The load is created in automation mode or protection circuit using normally close and normally open contact.

    Normally close: When its coil is not energized in normal close condition, its auxiliary contact is off.

    Normally open: Its auxiliary contact is open.

    Procedure of magnetic contactor

    When current passes through a contactor, an electromagnetic field is created and a magnetic field is generated. This magnetic field attracts the moving core.

    The core of the contactor starts spinning which helps to energize the moving contact. Moving and fixed contacts create short circuits. Through this the current passes through the next circuit.
    In the beginning the armature coil carries a lot more current. The passage of this current through the coil decreases very quickly. When the current stops, the coil is de-energized and the contact is opened.

    Why magnetic contactors are used?

       1. Many large motors or loads can be easily and safely controlled with the help of small push switches with magnetic contactors.

      2. Different signals or statuses are known through auxiliary contact (normally open and normally closed).

      3. It has an overload relay. If it is over current for any reason, it automatically interrupts the supply of load current.

      4. Three phase supply is to be given for three phase motor. Three phase supply can be easily given to the motor by using magnetic contactor.

      5. In case of Star-Delta, it can be easily controlled by using three magnetic contactors.

     6. When the power supply is turned off, the load current supply will be cut off. In this case, if you do not press the start button to re-supply current, the current will not be supplied to the load. This protects the device from surge voltage.

    Wiring Diagram Three Phase Star Delta Starter, Starter Motor Wiring Diagram:

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