Analysis and Treatment of Grounding Fault of High Voltage Motor Winding


Motor maintenance, analysis and treatment of ground fau […]

Motor maintenance, analysis and treatment of ground faults in high-voltage motor windings, has the advantages of high efficiency, energy saving, low noise, low vibration, light weight, reliable performance, and convenient installation and maintenance. It has been operating normally since it was put into operation, but in December of last year, the motor was protected during operation. The monitoring showed that the grounding signal of the motor stator winding appeared. After initial shaking the meter to measure the cable and motor insulation, it was found that there was a grounding phenomenon. We received the notice , Untie the cable connector in the motor junction box, and measure the cable and the motor with a 2500V megger. The measured insulation of the motor to the ground is 0.5MΩ and the cable is 3500MΩ, so it can be judged that the stator winding of the motor is grounded.

1. We know that the ground fault of the motor winding is nothing more than the following situations:

1. The motor is overloaded for a long time, and the insulation is aging and deteriorated to cause insulation to ground breakdown;

2, wire lightning overvoltage or operation overvoltage breakdown insulation;

3. When the synchronous motor suddenly disconnects the excitation coil, a high voltage will break down the ground insulation of the coil;

4. The creepage distance is reduced due to conductive dust, resulting in ground breakdown or flashover;

5. Ventilation ditch gasket, finger-shaped tooth pressure plate open welding or loose rivet, iron core is not tightly laminated, tooth flutter, and bent tooth pressure plate scrapes the coil insulation, resulting in winding ground fault;

6. ​​The insulation of the excitation coil of the asynchronous motor is aging and shrinking, and it often vibrates. When the motor is frequently started and braked, the insulation damages and breaks down to the ground;

7. Due to the short-circuit of the coil and the burnt insulation, the ground fault is caused

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