Common faults of capacitors. When one of the following conditions of the capacitor is found, the power supply should be cut off immediately.

(1) Capacitor housing expansion or oil leakage.
(2) The casing is broken, and there are flashover sparks.
(3) Abnormal sound inside the capacitor.
(4) The temperature indicator sheet falls off when the shell temperature rises above 55℃
Fault handling of capacitors

(1) When the capacitor explodes, immediately turn off the power and use a sand and dry fire extinguisher to extinguish the fire.

(2) When the fuse of the capacitor is blown, it should be reported to the dispatch and the circuit breaker of the capacitor should be opened after obtaining consent. Cut off the power supply to discharge it. First, conduct an external inspection, such as checking for any flashover marks on the outside of the casing, deformation of the casing, oil leakage, and short circuits in the grounding device. Shake the insulation resistance values between poles and between poles to ground, check if the capacitor group wiring is complete and firm, and if there is any missing phase. If no fault is found, replace the fuse and put it into operation. If the fuse still blows after power transmission, the faulty capacitor should be removed and power should be restored to the remaining parts. If the circuit breaker also trips while the fuse is blown, it should not be forcefully triggered at this time. It is necessary to wait until the above inspection is completed and the insurance is replaced before putting it into operation.

(3) If the circuit breaker of the capacitor trips and the shunt fuse is not broken, the capacitor should be discharged for three minutes before checking the circuit breaker, current transformer, power cable, and external components of the capacitor. If no abnormalities are found, it may be due to external fault bus voltage fluctuations. After inspection, it can be put into trial operation; Otherwise, further comprehensive power on tests should be conducted for protection. If the cause cannot be found through the above inspections and tests, it is necessary to follow the system and gradually test the capacitor. Trial investment is not allowed until the cause is identified.

Safety Matters


Safety precautions when handling faulty capacitors. The handling of faulty capacitors should be carried out after disconnecting the circuit breaker of the capacitor, opening the isolation switches on both sides of the circuit breaker, and discharging the capacitor bank. After the capacitor bank is discharged through a discharge resistor, discharge transformer, or discharge voltage transformer, due to some residual charges that cannot be discharged for a while, the grounding terminal should be fixed, and the capacitor should be discharged multiple times with a grounding rod until there are no sparks or discharge sounds. Then, the grounding card should be fixed. Due to the possibility of poor lead contact, internal wire breakage, or fuse melting in a faulty capacitor, there may still be some charges that have not been discharged. Therefore, maintenance personnel should wear insulated gloves before touching the faulty capacitor, short circuit the two poles of the faulty capacitor with a short circuit, and discharge them separately.