The handling of the faulty capacitor should be done after disconnecting the circuit breaker of the capacitor, opening the two isolation switches of the circuit breaker, and discharging the capacitor bank through the discharge resistor. After the capacitor bank is discharged by the discharge resistor (discharge transformer or discharge voltage transformer), because part of the residual charge cannot be discharged for a while, an artificial discharge should still be performed. When discharging, first connect the grounding terminal of the grounding wire, and then use the grounding rod to discharge the capacitor several times until there is no discharge spark or discharge sound, and then fix the grounding terminal. Since the faulty capacitor may have poor lead contact, internal disconnection or fuse blown, etc., some of the charge may not be discharged. Therefore, the maintenance personnel should also wear insulating gloves before touching the faulty capacitor, and first use a short-circuit wire to remove the faulty capacitor The two poles are short-circuited, and then they can be disassembled and replaced by hand.

For the neutral line of the double-star-connected capacitor bank and the series connection of multiple capacitors, the discharge should be performed separately.

Capacitors are electrical appliances with relatively weak reliability among various equipment in substations. They have weaker insulation than other equipment of the same voltage level. The internal components generate more heat, but the heat dissipation is poor, and there are more opportunities for internal failures. The internal material of the power capacitor has a large combustible content, so it is very easy to catch fire during operation. Therefore, the operation of power capacitors should be as good as possible to create good low temperature and ventilation conditions.

Repair of power capacitors

(1) The following types of failures can be repaired by themselves at the installation place:

①The oil leakage on the tank shell can be repaired with tin-lead solder.

②The oil leakage at the welding seam of the casing can be repaired with tin-lead solder, but the soldering iron should not be overheated to prevent the silver layer from desoldering.

(2) The capacitor has an insulation breakdown to the ground, the loss tangent value of the capacitor increases, and the case expansion and open circuit failures need to be repaired in a factory with special capacitor repair equipment.

Troubleshooting of capacitors in operation

(1) When the capacitor is sprayed with oil or explodes and catches fire, immediately disconnect the power supply and use sand or a dry fire extinguisher to extinguish the fire. Such accidents are mostly caused by overvoltages inside and outside the system, and serious internal capacitor failures. In order to prevent such accidents, the specifications of a single fuse must be matched. After the fuse is blown, the cause must be carefully found. The capacitor bank must not be used for reclosing, and the power must not be forced after the trip to avoid greater damage. .

(2) The circuit breaker of the capacitor has tripped, but the fuse of the shunt fuse is not blown. After the capacitor is discharged for 3 minutes, check the circuit breaker, current transformer, power cable and the outside of the capacitor. If no abnormality is found, it may be caused by external faults or bus voltage fluctuations. After the inspection is normal, it can be tested. Otherwise, the protection should be further subjected to a comprehensive power-on test. After the above inspections and tests, if the cause is still not found, the capacitor bank should be disassembled, and the inspection test should be carried out one by one. However, the trial operation is not allowed until the reason is found out.

(3) When the fuse of the capacitor fuse is blown, it should be reported to the dispatcher on duty, and after obtaining the consent, the circuit breaker of the capacitor should be disconnected. After cutting off the power supply and discharging the capacitor, first perform an external inspection, such as whether there are flashover marks on the outside of the casing, whether the casing is deformed, whether there is oil leakage, and whether there is a short circuit in the grounding device, etc. Insulation resistance to ground. If no signs of failure are found, you can replace the fuse and continue to operate. If the fuse of the fuse is still blown after the power is turned on, the faulty capacitor should be withdrawn and the power transmission operation to the remaining parts should be restored.