What tests should be done on the motor before repairing the mechanical fault?
In order to ascertain the cause of the fault and the approximate fault range, the following checks should be made on the outside of the motor before troubleshooting the motor mechanical fault.
1 Check the machine base and end cover for cracks, and whether the shaft has cracks or bending deformation.
2 Check whether the rotor rotation is flexible, stable, whether the axis is swimming, and whether there is abnormal sound.
3 Check if the bearing is loose or stuck.
4 Check the air duct for blockage, whether the fan blades and heat sinks are intact.
5 For motors with large capacity, the air gap is generally measured on the end cover, and the average value of the air gap non-uniformity can be detected within 15% by measuring the air gap.
6 Power-on operation, check whether the motor is normal by hand, ear, nose and eye. If an abnormality is found, the power should be cut off immediately to prevent the fault from expanding.
After the inspection determines the nature of the fault and clarifies the scope of inspection, the motor can be dismantled for further detailed inspection and repair.
For the mechanical part of the motor, the following checks should be made.
1 Check the surface of the rotor core for any scratches. When there is only one scratch on the surface of the rotor, and the surface of the stator is completely scratched, it is caused by bending of the shaft or imbalance of the rotor; when there is only one scratch on the surface of the stator, and the surface of the rotor is scratched every week, it is fixed. If the rotor is not concentric, such as the deformation of the base and the end cover, or the bearing wear is serious, causing the rotor to sink, etc.; if the surface of the rotor and the rotor have a large area of scratches, it is caused by the above two reasons.
2 Check whether the rotor core is aligned or not. If it is not aligned, it is equivalent to shortening the core, and the magnetic flux density increases to cause the iron core to overheat. The reason is that the rotor core is axially clamped or the new rotor is replaced. In addition, it should be checked whether the rotor core moves in the circumferential direction. If there is a movement phenomenon, the screw that loosens the stator is loose or damaged, or the rotor core does not fit tightly with the shaft.
3 Check the rotor end ring for cracks or breaks, whether the blades are damaged or deformed, and whether the shaft is bent or not.
4 Check the fit of the inner casing of the bearing with the journal and the bearing chamber. Do you have any over-tightening or looseness; check the bearing wear, whether the bearing is intact and whether the lubricating oil (fat) is too small or dry.
