Estimation of the type of low energy discharge in GIS adopting characteristic gas

In order to guarantee safe operations, low energy discharge within gas insulated switchgear (GIS) should be detected as soon as possible before they develop severely and cause final breakdown failures. This paper aims to present a GIS discharge diagnosis technique adopting gaseous decompositions. To reach this aim, needle-plate electrode and the sphere-plate electrode with metallic particles on the plate are designed to simulate two kinds of low energy discharge, namely, corona discharge and spark discharge, respectively. After sampling and analyzing the gases, different yields of gaseous by-products under different types of low energy discharge are obtained. Based on the decomposition mechanisms reported by previous researches and the experiment results, it can be concluded that S 2 OF 10 , SO 2 F 2 , and SO 2 can be used as the characteristic gas to identify low energy discharge; the increment of S 2 OF 10 can indicate the occurrence of low energy discharges while the volume ratio between SO 2 F 2 and SO 2 can define the type of low energy discharge.