The comparison of sensitivity between the UHF and ultrasonic methods for partial discharge detecting in GIS

In order to compare the sensitivity between the UHF and ultrasonic methods for partial discharge detecting in GIS, a 252kV GIS experimental platform was established. Four typical defect models are taken into consideration, including metal particle stuck on the insulator surface; free metal particle on the insulator surface; ground electrode defect and poor contact of high voltage electrode. Through the PD inception voltage and the PRPD (phase resolved partial discharge) spectrogram of UHF and ultrasonic signals, the sensitivity and feature of UHF and ultrasonic methods could be compared. The results indicate that: 1) Compared to the ultrasonic method, the UHF method could detect all four defects mentioned above with high sensitivity. 2) The ultrasonic method could only detect some models with high sensitivity.