High-voltage Disconnector Switch Operation And Maintenance Guide: Potential Hazards And On-site Troubleshooting For Auxiliary Switch Failures

In the daily operation and maintenance of substations, the auxiliary switches of high-voltage disconnectors, though seemingly insignificant, are often crucial in determining the reliable operation of the equipment. Auxiliary switch failures often stem from mechanical jamming in the transmission mechanism or poor contact in the secondary circuit contacts. Especially for outdoor equipment, after long-term operation, corrosion caused by inadequate sealing of the mechanism box often increases the resistance of the rotating parts of the auxiliary switch, leading to faults where the open/close position signals cannot switch normally.

Signal Abnormalities: Inconsistency between the Integrated Automation System and Field Display

When the monitoring system reports "inconsistent position signal" or "abnormal input," maintenance personnel must be highly vigilant. If the auxiliary switch of 111 cannot accurately rotate with the main contact, the most direct manifestation will be that the position displayed on the back-end machine does not match the actual open/closed state.

• Bus Differential Protection Risk: In a double busbar connection configuration, if the auxiliary contacts of the busbar-side disconnector have poor contact, the bus differential protection will detect the differential current and automatically report an "abnormal input" signal, which may seriously affect the correct judgment of the protection logic.

• Voltage Switching Failure: For line protection, auxiliary switch failure will directly lead to the voltage switching circuit's inability to operate normally. Once the switching relay fails to operate, the protection device will face the risk of AC voltage disconnection. If busbar reversal operation is performed at this time, it may even cause secondary voltage loss.

Mechanical Transmission and Contact Surface Inspection

For auxiliary switch failure, on-site troubleshooting should focus on whether the travel of the transmission linkage is complete. For high-voltage disconnecting switches with linkage drives, if the auxiliary switch contacts do not rotate to the correct position, it is usually due to insufficient mechanical rotation angle of the linkage or wear of the transmission shaft pin, resulting in a misalignment. Maintenance personnel should check whether the crank arm and linkage connection inside the mechanism box are secure. If necessary, the linkage can be manually pushed to verify whether the auxiliary contacts can produce a crisp "click" sound at the end of the opening and closing position. In addition, the contact pressure of the auxiliary switch itself and the oxidation condition of the moving and stationary contact surfaces are also key points of maintenance. The oxide film on the contact surfaces needs to be cleaned to ensure the continuity of the electrical circuit.