PROJECT TITLE :

Corrosion mechanism and process of hardware of disc suspension type Insulators on ±800 kV transmission lines

ABSTRACT:

Hardware corrosion on porcelain and glass insulators has occurred on ±800 kV UHVDC transmission lines in China. Iron cap corroded insulators all located at the negative polarity and pin corroded insulators focused in positive polarity. The corrosion mechanism is analyzed from the side of electrochemistry and also the corrosion process is researched by means that of spray water simulation tests. Mechanical and electrical characteristics tests and simulation calculation are done. Test and calculation results indicate that iron cap corrosion can worsen the contamination accumulation on insulator's surface and reduce the flashover voltage. Pin corrosion will decrease the mechanical strength of insulators. XP-4C kind porcelain insulator and electrolytic cell are used to research the influence factors of corrosion rate of hardware. The check results show that the contamination degree on insulators' surface and its component have considerable influence on the corrosion rate. The a lot of serious the degree of contamination is, the faster the corrosion rate is. The sequence of cation that lead to the corrosion rate from fast to slow is K+>Na+>Ca2+>Mg2+, the sequence for anion is Cl->SO42->NO3-.