Study on Grading Standards and Replacement Strategies for Rust Defects of Overhead Ground Lines of Transmission Lines

At present, the overhead ground cables of Tian-guang No.1 and No.2 circuit under the jurisdiction of China Southern Power Grid UHV Company have been in operation for more than 20 years. Due to the influence of operation life, natural environment and external forces, aging and rust are gradually occurring. Various operation and maintenance units are also carrying out the replacement of aging and rust overhead ground cables. However, there is no mature experience and standard for the corrosion grade and replacement strategy of galvanized steel strand. According to the previous experience of replacing old and corroded aerial ground wire of our bureau, combined with the appearance inspection of steel strand, stretching, wire splitting stretching, three point bending of steel strand, three point bending of wire splitting, winding of wire splitting, torsion of wire splitting and other test results, the technical paper is formed by referring to relevant literature. The grading standard, replacement time limit and key points of risk control of rust defects of aerial ground wire were clarified, and the daily maintenance, overhaul and replacement of old rusted aerial ground wire of the company and the industry were guided.