Experimental Investigation of Corona Onset in Contaminated Polymer Insulators

Polymer insulators, when contaminated, show an improved electrical performance compared to conventional insulators. However, there are long-term effects, caused by exposition of polymer surfaces to different kinds of contamination, which need studies. Among these effects are corrosion, treeing, degradation and insulation failures that occur due to long exposition of polymer to corona and partial discharges. This work aims to investigate the effect of contamination on polymer insulator surfaces under stress, and its influence on corona formation. Using a 15kV-class polymer insulator, experiments were performed to identify the corona onset voltage, under different contamination levels. At first, the influence of the position and volume of water droplets was investigated, using metallic…