Crackle discharge detection on GIS spacer through partial discharge test and decomposed gas analysis of SF6

Detection of crackle discharge on GIS spacer from the interferences such as corona in SF6 and surface discharge is of great interests in the evaluation of GIS health conditions. The spacer insulation deteriorates quickly when such discharges occur along small crackles on spacer surface. This paper presents two approaches to differentiate three types of discharges, i.e., corona in SF6, surface discharge and crackle discharge. The former can be distinguished from the latter two by analyzing the phase resolved partial discharge pattern. Further analysis of the decomposed gases accumulated from discharges reveals that CF4 is a useful indicator for discharge on spacer, and H2 occurs only with crackle discharge. Thus the combination of the above two measures provides powerful aids in the detection of crackle discharge in GIS.