RTV coating has a good anti-pollution flashover performance for electric power system.However

aging of RTV coating on insulator degrades its hydrophobicity.To understand the relationship between the pollution flashover voltage and the distribution of RTV coating’s hydrophobicity along an insulator string

this study conducted artificial pollution flashover tests for the insulator strings with RTV coating only on the insulator’s upper surface

lower surface

high electric field area

or low electric field area

which produces different uneven hydrophobicity distributions along the insulator strings.It was found that the flashover voltage of the insulator string with RTV coating on the lower surface is much higher than that with RTV coating on the upper surface under the same pollution grade

but there is no significant flashover voltage difference between the insulator strings with RTV coating on the high electric field area or on the low electric field area.The test results may provide a reference for evaluation of aged RTV coatings.