Partial discharge monitoring system for cubicle type GIS

Partial discharge (PD) monitoring system for cubicle type gas-insulated switchgear (C-GIS) filled with compressed dry air as an insulation gas was developed. The shield electrodes embedded in the solid insulator of bushings are used as PD sensors. For verification of the sensitivity of the sensors and propagation characteristics of PD pulse, artificial defects such as fixed particle on high voltage conductor and defect on creepage surface of insulator in C-GIS were used. It is clarified that the sensors had good sensitivity to PD pulse propagating along high voltage conductor in the range from VHF to UHF and that the amplitude of the sensor output had good correlation with apparent charge, pC, detected by conventional PD detector. The PD monitoring system is connected with our condition based maintenance (CBM) controller, which also monitors the abnormality of circuit breaker, disconnecting switch, gas pressure and so on, as a total diagnosis tool for our C-GIS.