In the previous article, we explained the little knowledge of AC contactors, and this time we want to let everyone know about the working principle of AC contactors, so that everyone has a thorough understanding of AC contactors, so that when you encounter them in the future, there will be a Good solution.
working principle
When the coil is energized, the static iron core generates electromagnetic attraction, which attracts the moving iron core. Since the contact system is linked with the moving iron core, the moving iron core drives the three moving contact pieces to move at the same time, and the main contact is closed, and the main contact is closed. The auxiliary normally closed contact mechanically connected to the contact is disconnected, and the auxiliary normally open contact is closed, thereby turning on the power supply. When the coil is de-energized, the suction force disappears, and the moving iron core linkage part is separated by the reaction force of the spring, so that the main contact is disconnected, the auxiliary normally closed contact mechanically connected to the main contact is closed, and the auxiliary normally open contact is disconnected , Thereby cutting off the power.
1. Generally, a three-phase contactor has a total of 8 points, three inputs, three outputs, and two control points. The output and input correspond, which is easy to see. If you want to add self-locking, you also need to connect the wire from a terminal of the output point to the control point.
2. First of all, you should know the principle of AC contactor. He uses an external power source to add an electromagnetic field to the coil. When the power is turned on, the contact point will be disconnected after the power is turned off. After knowing the principle, you should figure out the contacts of the external power supply, that is, the two contacts of the coil, which are generally on the lower part of the contactor and on each side. The other inputs and outputs are generally on the upper part, which can be known at a glance. Also pay attention to the voltage of the external power supply (220V or 380V), which is generally marked with. And pay attention to whether the contact point is normally closed or normally open. If there is self-locking control, just sort out the circuit according to the principle.
The carrying current of the AC contactor is very large. Generally, the internal pull-in coil is used to control its action. The control coil is operated by various types of relays connected in series with it. The trip will be caused by the AC after a lightning strike. The relay of the contactor has an overcurrent or grounding protection function. When there is lightning on the line, it will control the action of the AC contactor and cut off the load power to protect the equipment from high voltage, high current damage or grounding safety hazards .
Know the principle of AC contactor, and then operate or install it, it is very easy. But you still need to be careful during the installation process to avoid accidents.
