Study on diagnostic method of deterioration for power capacitors

For oil-impregnated type capacitors, thermal and electrical accelerating deterioration tests were conducted to study their various characteristics until their dielectric breakdown occurred. A diagnosis method for the deterioration analysis of gases dissolved in oil was also studied. CO+CO₂ gas is shown to be an effective index for the thermal deterioration. Since C₂H₂ is generated only by the partial discharge, it is possible to estimate the occurrence of partial discharge. While capacitors are deteriorated by thermal stress, it is considered that the dielectric strength of the insulating oil decreases due to gases dissolved in oil