As for the frequently happened damage of DC filter capacitor

in this paper

the fault mechanism and reason of DC filter capacitor for UHV converter station are studied and such tests as appearance and electrical performance

chromatography of insulation oil and capacitance dielectric loss of capacitor unit are performed. And such research tests as DC voltage breakdown of insulation entrapment of disassembled capacitor element and capacitor element at different temperature

AC and DC voltage breakdown of polystyrene film at different temperature as well as aluminum foil etc are carried out. It is found throughout comparative test and study between the faulty and good capacitors that instability of capacitor in operation is due to weak partial manufacturing process and oil filling process of the tested capacitor

and over concentration of resistance leads overheat of dielectric medium on surface of resistor and easy breakdown. The study result has important magnificence in improving operation reliability of such type of capacitor.