There are many factors that cant start the three-phase asynchronous motor. It should be analyzed and checked carefully according to the actual situation and symptoms. It is not allowed to start forcibly for many times. Especially when the motor makes abnormal sound or overheat, the power supply should be cut off immediately. After the causes are found out and eliminated, the motor can be started again to prevent the expansion of the fault. What is the cause of the motors failure to start?



1. The power is not connected



2. The fuse is blown



3. Open circuit of stator or rotor winding



4. Stator winding grounding



5. Phase to phase short circuit of stator winding



6. Stator winding wiring error



7. Overload or transmission machinery is jammed



8. Loose rotor copper bar



9. There is no lubricating oil in the bearing, and the shaft expands due to heating, which hinders the rotation in the bearing



10. Control equipment wiring error or damage



11. The over current relay is set too low



12. The oil cup of old starting switch is short of oil



13. Starting operation error of wound rotor motor



14. Improper rotor resistance of wound rotor motor



15. Bearing damage