Reasons for Corrosion Perforation of GIS Wall Bushing and Improvement Suggestions

Corrosion perforation of a GIS (gas insulated switchgear) wall bushing in a substation resulted in SF₆ leakage. The failure reasons for the GIS wall bushing were investigated through corrosion environment analysis and corrosion product detection combined with the location and morphology of corrosion. The results that the corrosive anion exuded from fire-proof package was the main cause of inducing electrochemical corrosion of the wall bushing. After the passivation film of aluminum alloy was destroyed, a passive-active corrosive cell formed on the surface of GIS wall bushing because of acidic environment constructed by acetic acid which was released by acidic glass gel, and then the corrosive cell finally became a serious pitting. According to the experience of past accidents, it was concluded that the process of GIS wall bushing could cause electrochemical corrosion under certain conditions, and some preventive measures were proposed.