For solving the problem of sharp drop of insulation performance of distribution network cover appliance at the condition of short-time rainfall and high humidity

the toughing hydrophobic nano-SiO

2

coating is uniformly sprayed on the surface of cover of insulator. The influence of hydrophobicity

surface discharge voltage and leakage current of three kinds of samples of insulator covers are tested and analyzed and the morphological distribution of water droplets on different surfaces is analyzed with combination of image recognition technology. It is shown by the test result that the hydrophob

icity of insulator cover coated with hydrophobic coating increases from HC5 to HC2. Under dry condition

the difference of dry flashover voltage of samples of the three different insulator covers is little and is within 5%. While

under the rain condition

the wet flashover voltage of P-El88 coating and CSS coating is higher than the sample without the coating by 75% and the leakage current is about 1/9 that of the uncoated sample. The duty ratio and particle size of water droplets on the hydrophobic coating surface are smaller than those of the uncoated surface. The application sample effect toughing hydrophobic coating P-EL88 is the best

which can enhance significantly the surface hydrophobicity of the cover appliance and improve its insulation performance at the rain condition.