High and low voltage complete sets of equipment: Maintenance and inspection of low-voltage switchgear
2025-04-28
Overhaul should start from the low-voltage side of the transformer. After the power distribution cabinet is de-energized, clean the dust in the cabinet, check whether the busbars and down conductors are well connected, whether there is any heating or discoloration at the joints, check whether the cable heads and wiring terminals are firm and reliable, check whether there is any rust on the grounding wires, and whether the wiring terminals are tightened. All secondary circuit wiring connections are reliable, and the insulation meets the requirements.
When checking the drawer-type switchgear, the drawer-type switchgear should be flexible when pushed in or pulled out, and the mechanical interlock should be reliable. Check whether the automatic air switch operating mechanism on the drawer cabinet is in place, and whether the wiring screws are tightened. Clean the dirt on and around the surface of the contactor contacts, check whether the contactor contacts are intact, and if the contacts are poor, slightly file the surface of the contacts if necessary. If the contacts are severely eroded (the contact point is worn to 1/3 of the original thickness), the contacts should be replaced. The power indicator instruments and indicator lights are intact.
When overhauling the capacitor cabinet, first disconnect the capacitor cabinet's main switch, and use a conductor of 10mm2 or more to discharge each capacitor to ground one by one. After the external inspection, the shell is intact and there is no oil leakage. If the capacitor shell is swollen, it should be dealt with promptly, and the discharge device, control circuit wiring screws, and grounding device should be replaced. After closing the switch, debug the indication part and the automatic compensation part.
Overhaul of circuit breakers in the receiving cabinet and connecting cabinet: After disconnecting all loads, manually pull out the circuit breaker with the handle. Re-tighten the wiring screws and check whether the knife edge elasticity meets the regulations. Check whether the arc extinguishing grid is cracked or damaged, whether the manual mechanical interlock switching is accurate, check whether the contact is good, file the contact surface if necessary, and check whether the internal springs, gaskets, and screws are loose, deformed, or fallen off.
Precautions:
1. A dedicated person must be assigned to supervise the overhaul process.
2. Electrical testing must be performed before work.
3. Overhaul personnel should be familiar with and operate the electrical and mechanical interlocking of the entire power distribution cabinet.
4. During the overhaul, it should be clearly understood which lines are dual-line power supplies.
5. When overhauling the busbars, the residual charge in the lines should be fully discharged.
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