1. Because the power supply voltage of the control circuit is lower than 85% of the rated voltage, the electromagnetic force generated by the electromagnetic coil after power on is small, and the moving iron core can not be moved quickly

2. The insufficient spring pressure causes the contactor to pull in abnormally; the excessive spring reaction causes the contactor to pull in slowly; the contact spring pressure overtravel

3. The gap between the dynamic and static iron cores is too large, the movable part is stuck, the rotating shaft is rusted or deformed, resulting in the abnormal closing of the contactor. Detachable when handling

At this time, it is not necessary to replace the lamination along the direction of flat plate

5. The short circuit ring is broken, which causes the abnormal sound of the iron core. In this case, the short circuit ring of the same size should be replaced.