Comparison of Surface Pollution Flashover Characteristics of RTV (Room Temperature Vulcanizing) Coated Insulators Under Different Coating Damage Modes

In recent years, room temperature vulcanizing (RTV) coated insulators have been increasingly applied in transmission lines. A large number of RTV coating damages on insulators are currently found. In this paper, three typical damage modes of the RTV coating were simulated, and then, the pollution flashover characteristics were studied. Results indicated that there is a big difference between the ac flashover performances of RTV coated insulators under different damage modes. The flashover voltage, as well as the critical leakage current, is largely influenced by salt deposit density (SDD), damage modes, and damage area. The relationship between SDD and U
₅₀
still meets negative power function when RTV coating was damaged. Insulators with fan-shaped damage have lowest flashover voltage and greatest critical leakage current. Both 2D and 3D FEM models of the RTV coating damaged insulator pollution layer were developed to calculate leakage current density on the damaged surface; it is discovered that the starting position of the arc usually occurs where the current density is maximum. Different damage modes lead to the change of the surface pollution layer conductivity and the uneven distribution of the current density, which is the main reason that pollution flashover characteristics are directly related to the damage modes.