Study on surface condensation behavior and flashover characteristics of superhydrophobic coating

Abstract

Condensation is one of the critical factors leading to insulation degradation or even failure of electrical equipment in high-voltage switchgear, thereby posing a serious threat to the safe and stable operation of the power system. Accordingly, a superhydrophobic room temperature vulcanized silicone rubber (RTV) coating based on perfluorinated-modified SiO2 nanoparticles is prepared to investigate its condensation behavior and flashover characteristics under high-humidity and temperature-differential conditions. Second, under temperature differences of 10, 20, and 30 °C, the condensation morphology and mass on epoxy resin, RTV, and the superhydrophobic coating are compared, and the flashover voltage and leakage current after condensation are measured. Finally, the motion behavior of water droplets under the influence of an electric field is analyzed, and the changes in electric field distribution during the droplet coalescence process are simulated using finite-element analysis. The results show that, compared with the surfaces of epoxy resin and RTV, the superhydrophobic surface maintains a consistently sparse distribution of condensed water droplets. At a temperature difference of 30 °C, the condensate mass on the superhydrophobic coating is only 0.53 ± 0.04 g (compared with 0.86 ± 0.05 for epoxy and 0.68 ± 0.04 g for RTV), corresponding to reductions of approximately 38% and 22%, respectively. The associated flashover voltage reaches 20.9 ± 1.3 kV (7.2 ± 1.2 kV for epoxy and 13.4 ± 1.3 kV for RTV), representing increases of about 190% and 56%, respectively. Simulation results indicate that the electric field force is strongly concentrated between the two droplets, driving them closer and increasing the central curvature. As the gap narrows and curvature grows, the local electric field strength and volumetric force density intensify, ultimately promoting droplet coalescence. This study provides a useful reference for applying superhydrophobic coatings in electrical insulation systems.