AC Pollution Flashover Characteristics of RTV Coatings with Non-Uniform Aging

RTV coatings have millimeter-scale non-uniform aging during operation, resulting in non-uniform distribution of hydrophobicity. However, the current research mainly focuses on the centimeter-scale RTV coating damage and does not pay attention to the non-uniform aging phenomenon, and their pollution flashover characteristics are not clear. Therefore, in this paper, a simplified non-uniform aging RTV coating model was designed, hydrophobicity test and artificial pollution flashover test were carried out, and leakage current and flashover process images were recorded. Hydrophobicity tests showed that the dynamic hydrophobicity of non-uniform aging RTV coatings decreased a lot, but still maintained global hydrophobicity. The pollution flashover voltage of the non-uniform aging RTV coating was 8.16 kV, which was 3.8% higher than that of the unaged RTV coating, but the sample variance was large. The leakage current suppression ability of the non-uniform aging RTV coating is reduced, leading to a significant occurrence of spot discharges in the RTV-glass mutation region, which will induce the formation of 4 to 6 dry bands, thereby effectively increasing the pollution flashover voltage. Overall, this study provides insights into the hydrophobicity distribution and pollution flashover characteristics of non-uniform aging RTV coatings.