The motor repairs are complete, but some motors still vibrate excessively. Is there any solution?
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The motor repairs are complete, but some motors still vibrate excessively. Is there any solution?
The adjustment shaft remains on a straight line, or there is a problem with the bearing. There are many possible causes, so a thorough inspection is required.
If it is a synchronous motor or a wound-rotor motor, care should be taken to adjust the air gap when removing and reinstalling the rotor
Under normal circumstances, a motor has one set of bearings that serve as positioning bearings (ball bearings or thrust bearings). If the wrong type of bearing is used, or if the fit between the inner ring of the bearing and the shaft is loose (it should be a tight interference fit), the rotor will experience axial movement during operation due to these issues, resulting in significant vibration.
Reasons for motor vibration: 1. Rotor dynamic imbalance caused by shaft bending, etc.; 2. Poor alignment; 3. Incorrect selection of the operating clearance of the bearings or poor assembly； 4. The distance between the geometric center and the center of the magnetic field lines is large. 5. The fit between the fan and the shaft is loose. 6. Partial blockage or misdirection of the cooling channels leads to uneven local overheating and expansion. 7. The air gap between the stator and rotor is uneven.
First, test the operation with a single motor, and then test it together with the load
It is necessary to make judgments based on the low level of vibration, the distribution of vibration values at the measurement points, the historical trend of vibration, and the waveform spectrum of vibration.
It’s quite comprehensive: 1. Rotor alignment – check whether the parts on the rotor have moved; 2. Perform dynamic balancing of the rotor; 3. Bearing clearance; 4. Pay attention to magnetic balance among the various poles during winding; 5. Whether the three-phase voltages are balanced :)
After learning this, one can listen to the sound of the bearings; if everything is normal, it’s likely that the alignment is poor. A measurement will confirm this. If vibrations are not the cause, then it’s probably a problem with magnetic imbalance.