What are the components of electromagnetic contactor? How does it work?

ontactor is a kind of automatic switching device that can frequently connect or disconnect AC and DC main circuits and large-capacity control circuits by using electromagnet operation according to external input signals. It is mainly used to control motors, welding machines, electric heating equipment, capacitor banks, etc. This article has collected and collated some materials, hoping to be of great reference value to all readers.

The electromagnetic contactor is mainly composed of transmission device (electromagnetic mechanism), contact device (actuator) and arc extinguishing device.

1. Electromagnetic mechanism

The electromagnetic mechanism includes three parts: moving iron core (armature), static iron core and electromagnetic coil. The current is applied to the electromagnetic coil to generate electromagnetic attraction to drive the contact to move.

Electromagnetic mechanism is one of the important components of electromagnetic contactor. The electromagnetic mechanism is composed of coil, iron core (static iron core), armature (moving iron core), pole shoe, iron yoke and air gap. The coil and iron core in the electromagnetic mechanism are not moving in the working state; The armature is movable.

The electromagnetic mechanism converts the electromagnetic energy generated by the electromagnetic coil into mechanical energy through the action state and process of the armature and the corresponding mechanical mechanism to drive the contact to close or open to achieve the control purpose of the controlled circuit.

2. Contact device

There are many structural forms of contacts, which can be divided into main contact and auxiliary contact according to the control circuit;

Contacts are divided into normally open contacts and normally closed contacts according to their original state;

Contacts are divided into bridge contacts and finger contacts according to their structure.

3. Arc extinguishing device

The arc-extinguishing hood is an insulated and high-temperature arc-extinguishing device made of clay and asbestos cement. It is a simple arc extinguishing device.

When the arc extinguishing device is used to extinguish the arc, the longitudinal seam arc extinguishing method is generally used in the arc extinguishing chamber to extinguish the arc.

Commonly used arc-extinguishing devices: arc-extinguishing cover (arc-resistant clay, asbestos cement, arc-resistant plastic), arc-extinguishing grid (arc-resistant grid sheet-copper plated steel sheet), magnetic blow-out device (a series of arc-extinguishing coils in the contact circuit).

4. Other components, including reaction spring, buffer spring, transmission mechanism and housing, etc.

Principle of electromagnetic contactor

The principle of the electromagnetic contactor is that when the electromagnetic coil of the contactor is energized, it will generate a strong magnetic field, which will make the static iron core generate electromagnetic attraction to attract the armature, and drive the contact to move: the normally closed contact is disconnected, the normally open contact is closed, and the two are linked. When the coil is powered off, the electromagnetic attraction disappears, and the armature is released under the action of the release spring to restore the contact: the normally closed contact is closed, and the normally open contact is disconnected. In industrial electrical, there are many types of contactors, with the current ranging from 5A to 1000A, which are widely used.

In electrical engineering, the contactor is an automatic switch used to connect or disconnect the AC/DC main circuit or large-capacity control circuit with load. The main control object is the motor. In addition, it is also used for other electrical loads, such as electric heaters, welding machines, lighting equipment. The contactor can not only connect and disconnect the circuit, but also has the function of low-voltage release protection. The contactor has large control capacity. Suitable for frequent operation and remote control. It is one of the important components in the automatic control system.