How to choose a contactor

The contactor is mainly composed of two parts of an electromagnet and a contact, and the contactor with a larger capacity also has an arc extinguishing device. When the coil is not energized, the open contact is called a normally open contact and the closed contact is called a normally closed contact. When the coil is energized, the electromagnet generates suction to attract the armature, causing the normally open contact to close and the normally closed contact to open. After the coil is de-energized, the electromagnet loses its suction force, the normally open contact is opened, and the normally closed contact is closed to realize the continuity of the line.

The selection of contactors should meet the following requirements:

(1) The rated working voltage of the contactor main contact should be greater than or equal to the rated voltage of the load.

(2) The rated operating current of the contactor main contact should be greater than or equal to the current of the load circuit. If the motor is controlled by a contactor, the rated current of the main contact of the contactor is generally reduced to one level.

(3) The breaking capacity of the contactor and the ability to withstand overload current should be higher than the current value that may occur in the circuit.

(4) The type of use of the contactor should be adapted to the requirements of the control object and operating conditions.