Common faults of low-voltage capacitors

1. Initial fault: there is a potential defect in the capacitor. In the initial stage of power supply, in case of abnormal situation, the fault will accelerate and worsen.

2. Occasional failure: the wiring is not firm during installation or damaged by external force.

3. Failure caused by overload use:

(1) The installation site is poorly ventilated and the ambient temperature is too high.

(2) Over-voltage operation: the operating voltage includes the change of power supply voltage, harmonic voltage and the rise of fundamental wave voltage after series reactor, which exceeds the maximum allowable over-voltage limit.

(3) Overcurrent operation: When the capacitor charging current contains harmonics, the effective value of the current shall not be greater than the allowable overcurrent limit.

(4) Capacitors used in automatic power factor adjustment panel (APFR) are frequently switched on and off with the change of load. If the surge current at the switching moment is not restrained, it will easily lead to capacitor failure and contactor contact damage.

4. Aging failure: After the capacitor is used for many years, the insulation strength is aging, the inside is free, and the electrical insulation strength is reduced, resulting in damage.