The maintenance of low-voltage distribution cabinet is mainly to ensure the normal and safe operation of low-voltage distribution cabinet. The low-voltage distribution cabinet shall be subject to annual general physical examination and maintenance. To complete the maintenance with the least power outage time, the owner’s power outage time is generally determined in advance.
Contents and steps of low-voltage distribution cabinet maintenance:
1. Maintenance should start from the low voltage side of the transformer. After the power failure of the power distribution cabinet, clean the dust in the cabinet, check whether the bus and down lead are well connected, whether the joint points are heated and discolored, whether the cable head and wiring pile head are solid and reliable, and whether the grounding wire is corroded and whether the wiring pile head is fastened. All secondary circuits are connected reliably and the insulation meets the requirements.
2. When checking the drawer switch, the drawer switch cabinet should be flexible when pushed in or pulled out, and the mechanical locking is reliable. Check whether the automatic air switch operating mechanism on the chest of drawers is in place and whether the wiring screws are tightened. Clean the dirt on and around the contact surface of contactor, and check whether the contact of contactor is in good condition. If the contact is poor, the contact surface can be slightly filed if necessary. If the contact is seriously ablated (the contact point is worn to 1/3 of the original thickness), the contact should be replaced. Power indicator and indicator light are in good condition.
3. When overhauling the capacitor cabinet, the main switch of the capacitor cabinet should be turned off first. After discharging the capacitor to the ground one by one with a wire of more than 10mm2, the shell should be visually inspected for good condition, and there is no oil leakage. If the capacitor shell expands, it should be handled in time, and the discharging device, the connecting screw of the control circuit and the grounding device should be replaced. After closing, debug the indicating part and automatic compensation part.
4. Maintenance of the circuit breaker in the power receiving cabinet and contact cabinet: disconnect all loads first, and then shake out the circuit breaker with the handle. Re-tighten the wiring screws and check whether the elasticity of the blade meets the requirements. Whether the arc extinguishing grid is broken or damaged, manually debug whether the mechanical interlocking opening and closing are accurate, check whether the contact is in good condition, file the contact surface if necessary, and check whether the internal spring, gasket and screw are loose, deformed and detached.
Maintenance of substation cabinet:
1. Before operation, the following steps should be followed: disconnect the load on the low-voltage side one by one, disconnect the circuit breaker on the high-voltage side, close the grounding switch, lock the high-voltage switch cabinet, and hang the sign "No closing, someone is working" on the handle of the switch cabinet, then short-circuit the bus bar with more than 10mm2 wires, hang the grounding wire, and tighten the bus bar screws.
2. Overhaul operation steps: wipe the contact of bus bar again, coat it with electric compound grease, fasten it with new spring washer screws, check whether there is any abnormality in the insulator and spacing connection between bus bars, and check the reliability of the connection of current, voltage and secondary winding terminal of transformer.
3. Inspection and test before power transmission: Remove all grounding wires and short wires, check whether there are any tools left on the job site, and after it is confirmed to be correct, close the isolating switch, disconnect the high-voltage side grounding switch, close the high-voltage side circuit breaker of the operating transformer, take down the signboard, and send power to the transformer, then close the circuit breaker of the low-voltage side power receiving cabinet, send power to the bus bar, and finally close the relevant contact cabinets and automatic air switches of each branch.