（1）Motor winding open circuit

    When the motor windings in one phase winding circuit, or parallel branch circuit, when there is a slip road, will result in three-phase current imbalance, so that motor overheating.

    （2）Motor winding short-circuit

    When the motor winding short-circuit fault occurs, the short-circuit current is much larger than the normal work, so that winding copper loss increases, resulting in winding overheating, or even burned.

    （3）Motor Connection Error

    When the triangle connected in the wrong then into a star-shaped electric motor, the motor is still working with a full load, the current flowing through the stator windings should be more than rated current, or even lead to electric motors on their own parking, if the stall time for a little longer is not yet cut off the power supply, winding not only seriously overheating, will be burned.When the star connection of motor fault then into a triangle when the windings and the core will overheat, severely burned when the windings.

    （4）Motor with reversed

     When one coil, coil group, or a reversed-phase winding, the three-phase current can lead to a serious imbalance, leaving winding overheating.

    （5）Motor mechanical failure

    When the motor shaft bending, assembly is not good, bearing defects, etc., will increase the motor current of copper loss and mechanical friction losses increased, the motor overheated.