Measurement of Leakage Current for Monitoring the Performance of Outdoor Insulators in Polluted Environments

The measurement of leakage current is used for monitoring the performance of insulators to minimize system outages attributable to pollution [1]. The technique is applied to transmission lines exposed to severe and varying conditions of pollution [2]. According to this technique, preventative maintenance is initiated when a critical level of current is reached on polluted insulators. However, the technique requires continuous supervision to analyze the condition of the monitored insulators. Important differences in the severity of pollution between sites can be detected by measuring the leakage current. In some sites, the severity of pollution can cause high leakage current activity in a short time, whereas in others, a longer time is needed and monitoring at different sites is necessary to determine the best insulator profile for each site. With the selection of the best insulator profile for each site, maintenance can be scheduled accordingly, thereby minimizing pollution flashover outages. Since 1995, the Mexican Electrical Research Institute (Instituto de Investigaciones Eléctricas), together with the Mexican electric utility (Comision Federal de Electricidad), has had several projects for online measurement of leakage current that have been applied to various designs of insulators in an attempt to minimize pollution flashovers on transmission lines [3]. To date, the Comision Federal de Electricidad has had 44 leakage current monitoring systems installed on several transmission lines [4]. © 2012 IEEE.