Sensitivity comparison of disc- and loop-type sensors using the UHF method to detect partial discharges in GIS

This paper investigates the sensitivity of two UHF sensors of a disc-type measuring electrode and a loop-type measuring electrode embedded in an epoxy insulator for detecting partial discharges (PD) and for diagnosing gas-insulated switchgear (GIS). The experimental results show that the disc-type electrode has a wide frequency range up to 8 (GHz), which is advantageous for detecting a particle on an enclosure. The results also show that the loop-type measuring electrode is more sensitive to a metallic particle on a conductor than the disc-type measuring electrode. These results confirm that both disc-type and loop-type measuring electrode are capable of detecting frequency components in the UHF range or in a higher frequency band up to 8 (GHz) when the different types of defect exist inside a GIS.