Regular maintenance of three-phase asynchronous motors

1. Mechanical inspection

Check whether there are cracks in the shell and end cover of the motor, weld if there are cracks, check whether the shaft is bent, and whether the assembly process is appropriate. In addition, use the hand to pull the rotor to see if it can rotate, if it does not turn to see if there is a foreign object stuck and whether the bearing is good, and then determine whether the bearing needs to be replaced according to the situation. Shaft sleeve measurement to check the upper and lower outer stops of the impeller and the size of the buckle ring and the inner diameter of the motor matched with them, whether the two matching gaps are within the scope of the maintenance standard, and it is necessary to replace parts or take other measures when the gap is out of tolerance, so that the matching gap meets the specified requirements, otherwise the performance of the motor is affected by axial balance force, etc. Observe and check the performance of the rotor, especially pay attention to whether there are abnormalities in the weld.

2. Electrical inspection

DC resistance inspection, three-phase resistance imbalance does not exceed 2%, insulation resistance inspection, three-phase asynchronous motor winding insulation resistance can generally reach 100Ω ohm or more, such as less than 5Ω need to analyze the reason, whether the insulation is damp, or winding due to poor insulation and grounding, etc., if the bridge experiment detects the three-phase resistance balance without problems, then pure insulation moisture, need to carry out drying treatment, such as stator three-phase resistance imbalance, then the motor coil three-phase respectively do the ground withstand voltage test and inter-turn experiment, find out the grounding point.