Capacitors that are connected in parallel with the load may be broken down. The capacitors are typically grouped on a capacitor rack. The group in which the capacitor is broken should be determined first. Disconnect the connection point between the busbar of each group of capacitors and the main busbar, and measure the resistance between the two busbars of each group of capacitors. Normally, it should be infinite. After confirming the bad group, disconnect the soft copper from each capacitor to the busbar and check the breakdown capacitors one by one. Each capacitor consists of four cores, one pole is the outer pole, and the other pole is led to the end cap through four insulators. Generally, only one core is broken down, and the lead on the insulator is tripped. Capacitors can continue to be used, with a capacity of 3/4. Another fault of the capacitor is oil leakage, which generally does not affect the use, but pay attention to fire prevention.

The angle of the capacitor is insulated from the capacitor holder. If the insulation breakdown will ground the main circuit and measure the resistance between the capacitor housing lead and the capacitor holder, the insulation condition of this part can be judged.