The characteristics and cause analysis of motor overload fault

Motor overload failure refers to the motor during operation to withstand the current exceeds its design rating, resulting in overheating, damage or stop working. The following are some characteristics and possible causes of motor overload failure:

Features:
1. Overheating: the surface temperature of the motor is abnormally high, and there may even be a burning smell.
2. Current exceeding: the current exceeds the rated current when the motor is running.
3. Speed reduction: motor speed reduction, serious may stop.
4. Sound and vibration: low sound and vibration occur when the motor is running.
5. Burnt odor and black smoke: When severely overloaded, the smell of burnt odor may be diffuse around the motor, and even accompanied by black smoke.
6. Winding damage: the insulation part of the winding is black and brittle, and the insulation layer is carbonized into powder when it is serious.

Reason analysis:
1. Heavy load: the actual running power of the motor exceeds the rated power, resulting in overload.
2. Lack of phase operation: one phase or polyphase of the three-phase power supply of the motor is missing, resulting in unbalanced operation of the motor.
3. Voltage problem: The operating voltage exceeds the allowable value of the rated voltage, resulting in heating of the motor winding.
4. Mechanical failure: such as bearing damage or mechanical blockage, resulting in motor speed reduction or stagnation.
5. Misoperation of the test process: such as the locked-rotor test time is too long, or the capacity of the test equipment is insufficient, resulting in overheating of the motor winding.
6. Wiring error: the star motor is wrongly connected according to the triangle connection method, or the voltage is too high when the motor is tested with different frequency and different voltage.
7. Power supply problem: the power supply voltage is too high or too low, resulting in winding heating.
8. Impact load: the load suddenly increases, resulting in a sudden decrease in motor speed.
9. Bearing system failure: bearing damage or sweeping stop, resulting in motor overload.

Troubleshooting method:
1. Check the load: confirm whether the motor correctly selects and matches the load.
2. Measure current: Use an ammeter or clamp meter to measure the actual power consumption of the motor and compare it with the rating on the nameplate.
3. Check the protection device: confirm that the motor starter protection device is correctly installed and adjusted.
4. Clean the vents: Regularly clean the motor surface and vents to remove debris that obstructs the airflow.
5. Check the motor wiring: ensure that the motor wiring is correct and there is no wiring error.
6. Check the power supply: Ensure that the power supply voltage is stable and within the allowable range.

Through the above characteristics and causes analysis, the motor overload fault can be effectively identified and treated to ensure the safe and stable operation of the motor.