A contactor is an automatic switching device that uses electromagnetic principles to control circuits. It drives mechanical contacts through a small current (the coil is energized to generate a magnetic field) to achieve the on-off of a large current main circuit. Its core structure includes an electromagnetic system (coil, iron core), a contact system (the main contact carries a large current, and the auxiliary contact is used to control the circuit) and an arc extinguishing device (to eliminate arcs). It is suitable for scenarios such as motor start and stop, lighting control, and industrial equipment power management. It has the characteristics of safety and reliability, strong frequent operation capabilities, and isolation of high and low voltage circuits. It is a key actuator in the automation control system.

Contactor Core components:

1. Coil: generates a magnetic field after power is turned on.

2. Iron core: enhances the magnetic field and attracts the armature.

3. Armature: moves under the action of the magnetic field and drives the contact to move.

4. Main contact: bears the on-off of the main circuit, usually 3 pairs of normally open contacts, used to connect the motor or power supply.

5. Auxiliary contact: used to control the circuit (small current) to achieve self-locking, interlocking or signal feedback.

Contactor Working principle:

1. Coil energization: When the coil in the control circuit is energized, the coil generates a magnetic field, attracting the iron core (armature) to move. The armature drives the contact system to operate, closing the main contacts and connecting the main circuit.
2. Main circuit connection: After the main contacts are closed, the current in the main circuit flows through the contactor to drive the load (such as a motor) to work.
3. Coil de-energization: When the coil in the control circuit is de-energized, the magnetic field disappears, and the armature is reset under the action of the spring. The main contacts are disconnected, the main circuit is cut off, and the load stops working.
4. Arc extinguishing: When the contacts are disconnected, an arc may be generated. Arc extinguishing devices (such as arc extinguishing grids and arc extinguishing hoods) are used to quickly extinguish arcs to prevent contacts from burning.

Contactor Wiring method:

In actual use, the control coil may have various types. Here we give two common voltages of 380V (connected to two-phase lines) and 220V (connected to one-phase line and neutral line), depending on the design of the contactor.
380V contactor:
Purpose: Usually used in three-phase circuits, it is necessary to connect to a three-phase power supply (L1, L2, L3).
Main contact wiring: The three-phase power supply (L1, L2, L3) is connected to the main contact input of the contactor, and the output is connected to the load (such as a motor).
Control coil wiring: The voltage of the control coil can be 380V (connected to two-phase lines) or 220V (connected to one-phase line and neutral line).
220V contactor
Purpose: Used in single-phase circuits, it is necessary to connect to a single-phase power supply (L and N).
Main contact wiring: The single-phase power supply (L) is connected to the main contact input of the contactor, and the output is connected to the load.
Control coil wiring: The voltage of the control coil is usually 220V (connected to the phase line and neutral line)