Questions regarding the maintenance of high-voltage motors
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It’s been unclear since when, but according to the regulations at our company, 10KV high-voltage motors need to be maintained once a year, and this maintenance is carried out by external service providers. The main tasks include replacing bearings, cleaning dust, and testing insulation. However, after such maintenance, most of the motors experience increased vibration. On the other hand, there are some motors that cannot be taken outside for maintenance; they can operate without any problems for around 10 years. How do you guys handle such motors?
There is no such thing as regular disassembly for inspection; moreover, excessive disassembly can cause the outer ring of the bearing to loosen. Regular lubrication is usually sufficient; check the insulation if necessary.
I also think it’s just looking for things to do, but what maintenance tasks do high-voltage motors actually require on a regular basis? Things like testing insulation or testing voltage resistance, for example?
This is a common situation; it also occurs in our company. After consulting with experts in electric motors, they said that even motors with rolling bearings need to have shaft fixation devices installed during transportation, in order to secure the shaft firmly. Otherwise, during transportation, the play in the bearings and the movement of the vehicle can cause slight movements between the inner and outer rings of the bearings as well as the balls, resulting in pseudo-Brinell indentations. This leads to excessively high acceleration values when measuring vibrations. Applying grease can help alleviate this issue; it is also possible to use grease with a higher viscosity. After disassembly, evenly spaced axial marks can be seen on the inner or outer ring of the bearing. I have experienced this situation and agree with it (after a motor is repaired, it emits a whistling-like sound after running for about 10 minutes; the acceleration is high, and applying grease can help alleviate the issue. Upon disassembly, it was found that there were evenly spaced axial indentations on the outer ring of the NU bearing on the drive side; at that time, it was assumed that the installation was incorrect, as the outer ring was installed before the inner ring had fully cooled down). However, I have not verified this myself (the motors in the factory are under the responsibility of the electrical department).