The main reason for the bulging of filtering power capacitors

On site investigation of filtering power capacitor faults in a certain region revealed that bulging faults accounted for a large proportion. The main reason for the analysis is the excessive pursuit of specific characteristic indicators during the initial configuration of filter parameters. The method selection is unreasonable and the analysis is not in-depth, resulting in a gap between the capacitor parameters and the grid parameters, insufficient rated voltage parameters of the capacitor, and relatively high working field intensity of the capacitor, which can easily lead to overvoltage operation of the configured capacitor.

Under the action of high electric fields, the dielectric in capacitors not only undergoes electrical aging, but also thermal aging due to high operating temperatures. Overheating can decompose substances in capacitors and produce gases. It can be seen that as the voltage across the capacitor increases, the actual capacity Q and heat generation P of the capacitor will rapidly increase with the square of the voltage, thereby increasing the temperature of the internal medium of the capacitor, accelerating the expansion of the capacitor, and causing bulging of the filtering power capacitor.