Motor rolling bearing is a kind of mechanical component which changes the sliding friction between the running shaft and the shaft seat into rolling friction, so as to reduce the friction loss. If the abnormal noise of rolling bearing is heard during the operation of motor, the machine shall be stopped immediately to check and analyze the cause and handle it. Causes of abnormal noise in rolling bearing of three-phase asynchronous motor and treatment methods: 1. The obvious rolling and vibration sound of the rolling element indicates that the bearing clearance is too large or severely worn and needs to be replaced. 2. The sound of the rolling body is hoarse and the tone is heavy, which means that the lubricating grease of the bearing is too dirty and there is impurity invasion. The bearing shall be cleaned with kerosene and replaced with new lubricating oil. 3. The rolling element has irregular impact sound, which means that some of the bearings are broken and need to be replaced. Generally, three-phase asynchronous motor shall be equipped with fault protection device, such as thermal protection device, motor electronic protector, etc., and the setting value selection of the protection device shall be adjusted according to the motor nameplate current. If the motor load is stable, in order to better protect the motor, the setting value of the protection device can be adjusted according to the actual working current of the motor. 4. Similar to the whistling sound, mixed with the rolling sound of rolling body, it indicates that the bearing is lack of lubricating grease or the selection of lubricating oil is improper, and it is necessary to add clean lubricating oil or replace appropriate lubricating oil. 5. Vibration sound is caused by aging bearing, loose foundation, unbalanced rotor, improper connecting shaft, poor matching, cracking of casing, etc. The stator three-phase winding of three-phase asynchronous motor is the circuit part of asynchronous motor, which plays an important role in the operation of asynchronous motor and is the key part to convert electric energy into mechanical energy. The structure of stator three-phase winding is symmetrical. Generally, there are six outgoing terminals in the junction box outside the frame, which are connected into star (y) or triangle as required.