Study on mechanical and electrical characteristics of gossans electrochemical corrosion ceramic insulators on DC transmission line

Chusui dc transmission line is the world´s first ±800kV transmission line in China. 2011 March, gossans of ceramic insulators on ±800kV Chusui dc transmission line appeared electrochemical corrosion at Qujing region in Yunnan province. The corrosion phenomenon concentrated in V-string insulators on negative polarity side. This article describes the basic electrochemical corrosion situation of ceramic insulators. In order to analyze the mechanical and electrical characteristics of electrochemical corrosion ceramic insulators of ±800kV Chusui transmission line, insulation resistance test, mechanical and electrical load destructive test and natural contamination flashover test had been done in National Engineering Laboratory for Ultra High Voltage Engineering Technology (Kunming). Test results indicate that gossans´ electrochemical corrosion problem didn´t obviously decrease insulators´ mechanical and electrical characteristic currently. The electrochemical corrosion insulators still satisfy transmission line´s operation requirements. Meanwhile, contamination degree of electrochemical corrosion insulators whose surface is divided into three parts had been measured respectively. Measurement results indicate the contamination severity of electrochemical corrosion products accumulated area on ceramic insulators´ surface is much heavier than other area, which indicates that ceramic insulators´ gossans electromechanical corrosion would aggravate contamination accumulation. It is necessary to take measures to suppress ceramic insulators gossans electrochemical corrosion.