1. The ambient temperature or room temperature for the installation of the electric motor is too high.

2. The cooling air duct of the motor is blocked, the fan blades are damaged, and the outer shell is covered in reverse, resulting in poor heat dissipation of the motor.

3. Overload operation.

4. Power supply overvoltage, undervoltage, or three-phase voltage imbalance.

5. Frequent start stop or frequent forward and reverse rotation.

6. Phase loss operation.

7. There are temporary objects around the motor, causing blockage of the air inlet and outlet.

8. The bearing is out of oil.

9. The motor or load mechanism is stuck and locked.

10. The load has too much rotational inertia and the startup time is too long.

11. Short circuit between turns of motor winding.

12. The internal wiring of the new motor is incorrect.

13. The winding star delta connection is incorrect.

14. The star triangle or self coupling voltage reduction starting load has a long restart time or fails to switch normally due to faults.

15. The motor winding is damp.

16. The rotor of the squirrel cage asynchronous motor is broken.

17. The rotor winding of a wound asynchronous motor is broken or the resistance is unbalanced.

18. The motor rotor is cleaned.

19. Excessive power harmonics, such as large rectifier equipment or high-frequency equipment nearby.

20. Changes in the performance of the motor core after multiple repairs.

21. The repaired motor winding was not constructed according to technical requirements.