Research on the electrolytic corrosion problem of porcelain insulator´s hardware on UHVDC transmission line

In recent years, hardware corrosion phenomenon occurred on several HVDC transmission lines in China, such as ±800kV Yunguang and Xiangshang UHVDC transmission lines, ±500kV Xingan, Gaozhao and Tianguang lines. The iron cap corrosion problem occurred on the negative polarity and pin corrosion emerged on the positive polarity of the transmission lines. The corrosion condition of iron cap on negative polarity and pin on positive polarity are introduced in this paper. Also, the corrosion mechanism and its disadvantage are analyzed respectively. At last, the suppression measures for iron cap and pin corrosion are proposed respectively according to the actual condition and research results. Test results indicate that the corrosion of iron cap will accelerate the accumulation of contamination and decrease the pollution flashover voltage. The corrosion of pin will decrease the mechanical strength of porcelain insulators. The installation of zinc ring and zinc sleeve is effective to suppress the corrosion of iron cap and pin respectively. The structure and size of zinc ring and zinc sleeve are designed in this paper.