This paper uses a 220 kV ABB silicone rubber insulator as shown in Fig. 1a; its dimensions are given in Table 1. The UNIGRAPHICS program was used to create the insulator model in 3-D and export it to the ANSYS program, where the material of the insulator was defined to be silicone rubber, as shown in Fig. 1b. In ANSYS program, appropriate finite-element meshes were then used for analysis, where the potentials at the ends of the insulator were ground at one end and the peak phase voltage at the other side.