Typical cases of electric field and voltage distribution calculations along polymer insulators under various wet surface conditions

The electric field and voltage distributions along wet polymer insulators are calculated using COULOMB, a three-dimensional electric field analysis software package. These distributions are distorted by the presence of water droplets on the surface of the insulators. The cases analyzed are based on several stages of the hydrophobicity classification (HC) recommended by the Swedish Transmission Research Institute (STRI). The models developed for the calculations are based on photographs of insulators undergoing aging tests in a fog chamber. The insulator surfaces of the cases selected for the calculations are characterized as HC1, HC2 and HC3. Electric field and equipotential lines and electric field enhancement factors on the surface of water droplets are presented.