When the AC contactor makes up, it is accompanied by vibration and noise, which is one of the common faults of the AC contactor. The causes of this fault are as follows:

    1. If the voltage of the control circuit is too low, only the AC contactor can be maintained. When the motor with large capacity starts, the circuit voltage drop is large, and the noise of the corresponding AC contactor is also increased, while the noise becomes smaller when the starting process is completed.

    2. The daily maintenance of the AC contactor is not paid attention to. In addition, the use time is long, resulting in dirt and sundries between the contact surface of the moving iron core and the static iron core, resulting in the increase of air gap and magnetic resistance. When the current in the line is over zero, although the short-circuit ring works normally, the distance between the poles becomes larger, which affects the normal operation of the short-circuit ring, resulting in the failure to overcome the reaction force of the recovery spring, resulting in vibration. If the AC contactor vibrates for a long time, it will cause the internal coil to burn.

    3. The mechanical failure of the AC contactor will seriously affect the normality of the AC contactor when it is closed. The reasons for the failure are usually aging due to the long-term use of the mechanical part, uneven or seriously skewed contact surface, skewed magnet or the main part of the rotating parts, serious wear of the iron core pole, etc.

    4. When the contact spring of the AC contactor is deformed due to high temperature and mechanical damage, resulting in pressure change, corresponding adjustment is required to ensure the normality of the AC contactor when it is closed.