What should I do if a solid capacitor is found to be faulty?

Summary: Capacitors are one of the most widely used electronic components in electronic ...
Capacitors are one of the most widely used electronic components in electronic equipment. They are widely used in circuits such as direct current isolation, coupling, bypass, filtering, tuning loops, energy conversion, and control.



How to deal with solid capacitors when faults are found?
1. Common failures of capacitors. When one of the following conditions of the capacitor is found, the power supply should be cut off immediately.
(1) Capacitor shell expansion or oil leakage.
(2) The casing is ruptured, flashover occurs and sparks occur.
(3) The internal sound of the capacitor is abnormal.
(4) The temperature of the shell rises above 55°C and the temperature indicator sheet falls off.


2. Troubleshooting of capacitors
(1) When the capacitor explodes and catches fire, immediately disconnect the power supply and use sand and a dry fire extinguisher to extinguish the fire.
(2) When the fuse of the capacitor is blown, report to the dispatcher, and open the circuit breaker of the capacitor after obtaining the consent.
Cut off the power supply to discharge it, and perform an external inspection first, 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., and measure the insulation resistance between the poles and the pole to the ground. Check whether the capacitor bank wiring is complete and firm, and whether there is phase loss. If no failure is found, you can change the insurance and put it on.
If the fuse is still blown after the power is supplied, the faulty capacitor should be withdrawn and the power supply to the remaining parts should be restored. If the circuit breaker trips at the same time as the fuse is blown, do not force it. After the above inspection is completed, the insurance must be replaced before investment.
(3) The circuit breaker of the capacitor is tripped 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 the outside of the capacitor. If no abnormality is found, it may be caused by external fault bus voltage fluctuations.
After inspection, it can be tested; otherwise, a full power-on test of the protection should be carried out. Through the above inspections and tests, if the cause is still not found, it is necessary to act according to the system and gradually test the capacitors. No trial investment is allowed until the reason is ascertained.


3. Safety matters when handling faulty capacitors. To deal with the faulty capacitor, after disconnecting the circuit breaker of the capacitor, open the isolation switches on both sides of the circuit breaker and discharge the capacitor bank.
After the capacitor bank is discharged by the discharge resistor, the discharge transformer or the discharge voltage transformer, because part of the residual charge can not be discharged for a while, the grounding terminal should be fixed, and then use the ground rod to discharge the capacitor several times until there is no spark or discharge sound. , And then fix the grounding clamp.
Since the faulty capacitor may have poor lead contact, internal disconnection or fuse, there may still be some charges that have not been discharged. Therefore, the maintenance personnel should wear insulating gloves and short-circuit the faulty capacitor before touching the faulty capacitor. When the two poles are short-circuited, they should be discharged separately.