Electric field distribution analysis of polluted composite insulators based on COMSOL

In humid weather conditions, contamination on the surface of composite post insulators becomes wet. Under the thermal effect of leakage current, this wet contamination may lead to the formation of dry bands, which can trigger flashover accidents. Based on this, COMSOL software is used to analyze the electric field distribution of insulators under polluted conditions and after the formation of dry bands. The results indicate that the electric field intensity on the surface of contaminated insulators is significantly higher than that of clean ones, making field distortion more likely. Wet contamination adhering to the insulator surface forms dry bands under the influence of leakage current. The thinner the wet contamination layer and the higher its conductivity, the greater the leakage current density. The leakage current between the sheds is higher than that on the upper and lower surfaces, making dry bands more likely to form in these regions. As the width of the dry band increases, the electric field strength on the upper and lower surfaces of the shed groups increases, while the field strength between the sheds decreases. In all cases, the maximum electric field intensity occurs at both ends of the dry band. When a dry band forms between sheds, it has the most significant impact on the surface electric field of the insulator. Moreover, as the number of dry bands increases, the overall surface electric field intensity tends to decrease.