The role and working principle of AC contactors

AC contactor is a commonly used electrical control device, which is usually used to control the switching and operation of high-power electrical equipment. This article will introduce the role and working principle of AC contactor in detail.

First, the role of AC contactor

AC contactors are mainly used to control the switching and operation of electric motors and other high-power loads. It realizes motor control and protection by controlling motor start, stop, forward and reverse actions. At the same time, AC contactor can also be automatically adjusted and controlled according to external conditions or instructions to realize the function of automation control system.

The working principle of AC contactor

The working principle of AC contactor can be divided into two aspects: electromagnetic suction and mechanical transmission.

Electromagnetic suction

The suction coil of AC contactor is the key component, which can generate enough magnetic field to attract and suction contacts. AC power is supplied to the contactor through the main and control circuits. When sufficient voltage is applied to the control circuit, current passes through the suction coil, generating a magnetic field. The magnetic field attracts the iron core, causing the contacts to close. The closed contacts are able to conduct the supply current and drive the load.

Mechanical Transmission

The mechanical transmission part of the AC contactor includes the iron core, spring, contacts, pins, etc. When the suction coil generates a magnetic field, the magnetic force causes the iron core to attract and suction the contacts. The closure of the contacts is displaced, which exerts pressure on the iron core and pin. The contacts need to overcome a certain amount of rebound force during closure and separation to ensure reliable switching operation. When the suction coil is energized and de-energized, the magnetic field disappears, and the contacts are quickly separated due to the rebound force of the spring and the action of the pin, opening the circuit.

Third, the structure and working process of AC contactor

The structure of AC contactor includes fixed contact, moving contact, spring, release coil, central universal joint bar and so on. These parts realize electromagnetic action and mechanical conduction through reasonable installation and combination to complete the switching action.

Suction-close process

When sufficient voltage is applied to the control circuit, current passes through the suction coil, generating a magnetic field. The magnetic field attracts the iron core and closes the movable contact. At this point, the current flows from the fixed contact to the movable contact, into the load, and the motor begins to run.

Power failure process

When the voltage of the control circuit drops or is interrupted, the suction coil is no longer energized and the magnetic field disappears. At this time the force of the spring separates the movable contact quickly and opens the circuit. The motor stops running.

Release process

When the control circuit is energized again, the release coil generates a magnetic field. The magnetic field exerts a gravitational force on the iron core, causing the contacts to close. The motor restarts.

Features and Advantages of AC Contactors

AC contactors have many features and advantages, including high reliability, small size, light weight, low power consumption and so on. The specific performance is as follows:

High reliability: AC contactors have stable electrical performance and mechanical strength, and can withstand high frequency and high load working environment to ensure stable operation for a long time.

Small size: AC contactors can be small in size, easy to install and arrange in the electrical control box, saving space.

Light weight: AC contactors are light in weight due to the use of high quality materials and reasonable structural design.

Low power consumption: AC contactors have low power consumption in the working process, which can effectively reduce the waste of energy.

To summarize, AC contactor is an important device widely used in the control of electric motors and other high-power loads. It realizes the closing and separating of the switch through the working principle of electromagnetic suction and mechanical transmission, so as to realize the starting and stopping of the motor and the control of the working state. AC contactor has the advantages of high reliability, small size, light weight and low power consumption, so it is widely used in industrial and civil fields.