Analyses and Improvement Measurements for Oxidation of Terminal Connector Used for Overhead Lines

Terminal connectors for double conductors (bolted type) are used in 35 kV substation, severe oxidation corrosion was found during a routine inspection. The causes were studied by means of macrography, chemical composition analysis, SEM and energy spectrum analysis. The external causes made the terminal connector severely oxidized and corroded were contact resistance between connector and wires, damage of insulation cover, corrosion effect of rain water and other atmosphere composition. Improperly selected material for the terminal connector and excessive amount of Zn content were the internal causes of pitting corrosion and intensive distribution of etching pits on the surface of terminal connector. Some suggestions, such as controlling alloy composition and content, reducing the contact resistance between connector and wires, checking the tightness of insulation cover during substation routine inspection, were provided for safet operation of substation equipment.