On-line leakage current monitoring of 400 kV insulator strings in polluted areas

Abstract

The insulation of the 400 kV transmission lines located in the northeast part of Mexico (Monterrey) have experienced flashover problems due to pollution accumulation. Several actions have been taken to increase reliability (washing, use of RTV coatings, insulators with longer leakage distance, etc.). In order to help the maintenance work on these lines, a system for the measurement of leakage current and surface resistance of insulators has been developed. The system was installed in several towers along the line as a diagnostic tool to monitor the surface condition of the polluted insulation. The development, laboratory tests and installation of the system in the field are reported.