The Effect of Temperature on Characteristics of Partial Discharge Induced by Metal Tip in GIS

Partial discharge (PD) induced by metal tip is one of the most common types in gas insulated switchgear (GIS) equipment. However, the evolution of its characteristic under realistic in-service temperature stresses has not been sufficiently clarified. In this paper, a GIS prototype test platform was constructed to reproduce the actual gas temperature distribution inside the chamber, and a detection system including ultra-high frequency (UHF) sensor and photomultiplier tube (PMT) was integrated, to investigate the PD behavior caused by a metallic tip mounted on the central conductor, with the tip oriented either downward or upward in separate tests at different temperatures. The results indicate that, as the temperature increases, the PD inception voltage (PDIV) of the downward-oriented tip gradually decreases. In contrast, the PDIV of the upward-oriented tip remains almost unchanged. Regarding the repetition rate, for the downward orientation, only the negative PDs measured by the UHF exhibit a noticeable increase with temperature in the intermediate stage of PD development, whereas the other cases show slight variations. For the upward orientation, the UHF-based repetition rate of positive PDs decreases with increasing temperature, whereas that of negative PDs increases. In terms of amplitude, the average UHF pulse amplitude for both polarities decrease with temperature when the tip is oriented downward. In contrast, for the upward-oriented tip, the average amplitude of positive PDs measured by both UHF and PMT decreases with temperature, while the amplitude of negative PDs increases, and the negative PD amplitude–voltage characteristic exhibits a concave shape, i.e., it first decreases and then increases with voltage. These findings will provide helpful guidance for PD pattern recognition and insulation condition assessment in on-site GIS.