vacuum pump motor trouble shooting

The motor fault of vacuum pump is also one of the common problems of vacuum pump. The following are the common faults and troubleshooting methods of vacuum pump motor. The faults of AC motor are various, the same fault may be different, and the same phenomenon may be caused by different reasons. It is necessary to grasp the essence through the phenomenon so as to judge accurately and prescribe the right medicine.

Vacuum pump motor fault can be divided into mechanical and electromagnetic two categories: the former, such as scavenging (rotor outer circle and stator inner circle rub), bearing wear, etc., the latter mainly occurs in the winding. The principle of inspection is external before internal, mechanical before electromagnetic.

To judge the fault, we should first understand the situation of the fault, especially the changes before and after the fault. Observe whether the motor has any abnormal conditions, such as the end cover, fan, end cover and casing are loose, cracked or damaged, whether the air path is blocked, whether the shaft is bent, whether there is any special smell, and identify whether it is the smell of burning insulating paint or the smell of melting and evaporation of lubricating grease, or other. Rotate the rotor by hand, and listen to whether there is friction of foreign matters or friction of stator and rotor core. If the motor can still be started, pay attention to whether there is abnormal sound during starting and operation. And touch each part of the motor by hand to check the degree of heating and whether there is local overheating (such as heat near the bearing chamber compared with other parts) and vibration.

The winding damage of different step motor is largely caused by the operation of phase loss. The so-called phase loss operation refers to the sudden power failure of one phase of the motor in operation, while the motor is still working, because the current is too large, it is bound to burn the winding. When phase loss operation occurs, the motor sound is extremely abnormal, and the power supply shall be cut off immediately after discovery for shutdown inspection.

In addition, winding short-circuit fault is also common. Winding short-circuit can be divided into one phase winding short-circuit to ground, two-phase winding inter phase short-circuit and one phase winding inter turn short-circuit. When the insulation between the winding and the core is damaged, there will be a ground fault. Due to the large current, the ground winding may be burnt out or the fuse fuse may be fused, resulting in phase loss operation. If the enclosure is not grounded reliably in advance, electric shock may be caused due to the electrification of the enclosure. It is not difficult to determine the method of megger or series bulb test for ground fault. In addition to the insulation damage, the phase to phase short circuit can also be caused by metal foreign matters inside the motor (such as iron chips, aluminum chips, screws, wire heads, solder beans, etc.). Turn to turn short circuit is the short circuit between the conductors of a phase winding itself, so the effective turns of the winding are reduced and the current is too large. Turn to turn short circuit can be checked by making a short circuit detector based on transformer principle.