Troubleshooting Common Faults in Mining Switchgear

Mining switchgear operates in harsh environments (humid, dusty, large voltage fluctuations), resulting in diverse fault types. Systematic fault handling knowledge is crucial for ensuring safe power supply in mines. The following are common fault handling procedures:

1. Insulation Fault

Symptoms: Discharge sounds or unusual odors inside the switchgear; insulation monitoring device alarms; leakage protection trips.

Causes: Humid environment and high dust levels lead to contamination and moisture accumulation on insulator surfaces; equipment aging and deterioration of insulation material performance; aging and damage to cable joints or terminals; surge arrester breakdown.

Solutions:
① Clean and dry the surfaces of insulating components after shutdown;
② Measure the insulation resistance to ground and between phases using a megohmmeter;

③ Dry the inside of the cabinet and improve ventilation and dehumidification.

 

2. Refusal to Open/Close

Symptoms: After pressing the close button, the electromagnet activates, but the circuit breaker contacts fail to close.

Causes: No voltage in the control power supply; secondary circuit fault; mechanical fault in the operating mechanism, such as jammed transmission components, excessive clearance, or uncharged energy storage spring.

Troubleshooting:

① Check the control circuit voltage and fuses; measure if the voltage is normal.

② Disconnect the power supply, manually test the opening and closing of the circuit breaker, clean the iron core, and add lubricant.

③ Measure the resistance of the closing coil; a normal value is several tens of ohms. If there is a broken wire or short circuit, replace the coil.

 

3. Malfunction

Symptom: The switchgear trips automatically without any operation signal during normal operation; cascading tripping occurs when specific equipment starts.

Causes: Improper protection settings; electromagnetic interference causing false triggering of the control circuit; water ingress or moisture in the mechanism box causing short circuits in auxiliary contacts.

Solutions:

① Record the fault code, verify and recalculate the setting matching degree;

② Check electromagnetic compatibility and implement shielding measures for signal lines;

③ Seal gaps in the cabinet and install a heater to remove moisture.

 

4. Leakage Fault

Symptom: The leakage interlock function is activated, and the switch cannot be closed.

Causes: Damaged insulation on the load-side cable or moisture in the motor; damaged insulation of internal terminals and wires in the switch causing grounding.

Solutions:

① Disconnect the load cable and test the switch individually to determine whether the leakage point is inside or outside the switch;

② If the fault is inside the switch, focus on checking the insulation of the main circuit components.

 

5. Cabinet Overheating

Symptoms: Abnormal temperature rise on the cabinet surface; infrared thermometer shows excessively high temperatures at contacts or busbar connections; a burning smell is present.

Causes: Poor contact in the conductive circuit; prolonged overload operation; poor ambient heat dissipation; blocked ventilation holes.

Solutions:
① Tighten the back-tightening circuit connection bolts after power failure; inspect and replace worn contacts;

② If the detected current exceeds the rated value, adjust the load or replace with a higher-capacity switch;

③ Clean the ventilation openings and cooling fan.