1.Failure judgment and cause analysis of parallel capacitors
(1) Oil leakage. Oil leakage of shunt capacitors is a common phenomenon, which is mainly caused by poor product quality, improper operation and maintenance, and lack of maintenance in long-term operation, resulting in rust and corrosion of the outer skin.
(2) The capacitor shell expands. Due to the action of a pit electric field, the insulator inside the capacitor is freed, gas is decomposed or some components are broken down, and the electrode discharges to the outside, which increases the internal pressure of the sealed casing and causes the casing to expand and deform.
(3) The temperature rise of the capacitor is too high. The main reason is that the capacitor follows the current and poor ventilation conditions. For example, unreasonable outdoor adjustment of capacitors causes poor ventilation; long-term overvoltage operation of capacitors causes capacitor overcurrent; high-order harmonics generated by rectifier devices cause capacitors to overcurrent, etc. In addition, the failure of the internal components of the capacitor, the aging of the dielectric, the increase of the sine value of the dielectric loss, and the increase of the sine value of the dielectric loss angle may cause the capacitor to increase in temperature. The increase in the temperature of the capacitor will affect the life of the capacitor, and may also cause insulation breakdown and short-circuit the capacitor.
(4) Flashover discharge on the surface of the capacitor porcelain bottle. The reason is that the porcelain insulation is defective and the surface is dirty.
(5) The sound is abnormal. If there is a discharge sound or other abnormal sound during operation, it means there is a fault inside the bladder capacitor.
(6) The capacitor bursts. Where there is a breakdown of the insulation between the poles or the casing, other capacitors connected in parallel with it will release a large amount of energy to the capacitor, which will cause the capacitor to burst and cause a fire.