Real-time monitoring of leakage current on insulating cross-arms in relation to local weather conditions

Two insulating cross-arms have been installed within a trial site near the coast of Northeast Scotland, energised at 231 kV. The trial aims to observe the electrical behaviour of the cross-arm by monitoring in real time the leakage current of the insulating members. The weather monitoring equipment installed at the site records wind speed and direction, precipitation, atmospheric pressure, temperature, relative humidity, visibility and solar irradiance. The instrumentation is complemented by cameras that provide visual verification regarding the conditions at the site. The results from the trial during June 2012 show that the cross-arm performs according to design expectations. The leakage current profile of the novel compression insulators is similar to that of the industry standard tension insulators. A relative humidity threshold of 90% has been identified which if exceeded, results in increased leakage current activity. Additionally it has been found that the prevailing wind affects the south facing cross-arm more than the west facing one. Also, the effects of precipitation have been found to be more prominent on the tension members.