Abstract
The deterioration products formed due to partial discharge in a void filled with sulfur hexafluoride (SF6) were analyzed. The SF6 content in the void decreased with ageing; after about 15h of ageing, the SF6 content was about 15%. Then, after 24h of ageing, spots of powder formed on the void surface. When the powder was exposed to air, it changed into a colorless liquid. It was determined that this liquid was sulfuric acid (H2SO4) and thus, the powder was sulfur trioxide (SO3). According to ESCA analysis of the void surface after 100h of ageing at 21kVpeak, S2s and S2p spectra were observed. However, they were not detected in the virgin sample. This result shows S atom exists on the void surface, but the process is still not clear.
