When the motor is in an abnormal working state (including electrical, mechanical and environmental aspects), the life of the motor coil will be seriously shortened. The reasons for the failure of the fan coil are: phase loss, short circuit, coil grounding, overload, rotor lock, voltage imbalance, and surge. Below are pictures of various coil failures to help you correctly identify the cause of the failure (take a 4-pole motor as an example).。

1、New coil picture

2、Lack of phase

The lack of phase is the open circuit of one phase of the power supply, the main reason is that the fuse of one phase is blown, the contactor is open, or the power line of one phase is broken.

Star connection (Y connection) Delta connection

The picture above is a picture of a 4-pole motor being burnt out of phase loss. Symmetrical burnout of the motor coils is a phase-lack burnout. If the star connection method is out of phase, it is good for a 2-pole motor to only have 2 sets of coils, and a 4-pole motor to symmetrically burn out only 4 sets of coils. The set of coils is good; if the delta connection is out of phase, the 2-pole motor burns 2 sets of coils symmetrically, and the 4-pole motor burns 4 sets of coils symmetrically.

3、Short circuit

The following pictures illustrate that motor failure is caused by contamination, wear, vibration, etc.

Short circuit between phases Short circuit between turns

4. Coil grounding

The following pictures illustrate that motor failure is caused by contamination, wear, vibration, etc.

Motor notch breakdown Inter-slot breakdown

5. Overload

Overloading the motor will cause the motor to overload.

Note: Both under-voltage and over-voltage can cause insulation damage and cause overload.

6. The rotor is locked

This situation will cause a lot of heat in the motor, most likely due to frequent starting or frequent reversal of the motor.

7. Uneven three-phase voltage

Uneven voltage will cause insulation damage, which may be due to unstable power supply and poor wiring.

Note: A one percent voltage imbalance can cause a six to ten percent current imbalance.

8、Surge

The situation shown in the figure below is generally caused by a power surge. Power surges can be caused by electrical equipment such as power grids, lightning, capacitors, etc.