Enhancing Insulation Defect Detection in GIS: Comparative Study of Photon Counting, UHF, and Conventional PD Measurement Methods

High-sensitivity detection of metal contaminants during gas-insulated equipment (GIE) manufacturing is crucial to mitigating insulation risks. In this study, detection tests of metal contaminants are performed using the conventional partial discharge measurement (CPDM), UHF, and photon counting (PC) methods on a 252 kV GIS chamber. The results indicate that the PC method exhibits high sensitivity to micrometer-sized metal dust, while the UHF sensor performs better in detecting the millimeter-sized single wire-shaped particle. The CPDM method has no sensitivity advantage in either of the above cases. For sub-millimeter-sized block contaminants, all three methods exhibit comparable sensitivity. Moreover, a comprehensive statistical index is introduced to evaluate the discharge activity of different metal defects, enabling a more robust quantitative comparison.