If abnormal conditions such as severe oil leakage, deformation, heating, porcelain damage, or internal discharge are found in capacitors, the capacitor bank should be taken out of operation promptly.
If a capacitor explodes or catches fire; if the connector is severely overheated or melted; or if severe discharge flashover occurs on the bushing without the switch tripping, the capacitor switch should be opened immediately.
After the capacitor bank switch trips, it is not allowed to force reclose. The operator must analyze and judge based on the protection action. If it is an overcurrent protection action, focus on checking the external circuit of the capacitor:
Check whether there is any grounding or short circuit phenomenon on the current transformer, power cable, and leads, and whether any foreign objects have fallen on them. If it is an unbalanced protection action, it may be that one or several capacitors have internal damage. In this case, the focus of inspection should be on the capacitors themselves.
When handling after a capacitor accident, each capacitor must be discharged one by one. The outer shell of capacitors mounted on insulated supports should also be discharged to ground. When discharging, first fix the grounding end, then use a grounding rod to discharge between the capacitor poles and from the poles to ground multiple times until there is no spark or discharge sound. Since faulty capacitors may have poor lead contact, internal disconnection, or blown fuses, some charge may not be released. Therefore, before touching the faulty capacitor, maintenance personnel should also wear insulating gloves and use a short-circuit wire to short-circuit the two poles of the faulty capacitor before disassembling it.
When replacing capacitors, the capacitance values of each phase should be balanced. For double-star wiring, the capacitance values of the same phase in the two groups should be balanced, and the number of capacitors in the two groups should be as consistent as possible; if not, the difference should not be too large.
