Dry Band Formation and Its Influence on Electric Field Distribution along Polluted Insulator

The formation of the dry band has great influence on the electric field distribution along insulator, which will result in the partial arc as well flashover. In order to investigate the characteristics of dry band under different conditions, a three-dimension model of polluted insulator is established in this paper. The formation, location, width and number of dry band and its effect on the potential and electric field distribution are investigated based on the analysis of electric field using the finite element method. The results show that there will be obvious distortion of the electric field distribution of insulator when the dry band appears on the surface of polluted insulator. The maximum electric field of dry band is related to its location on the insulator surface, it has a trend of asymmetric U type along the axial direction on the surface of insulator. The dry band on underside surface of the insulator has a greater influence on the electric field distribution than that on upper surface. The maximal value appears on the center of dry band, which increases with the growth of dry band angle along the circumferential direction along the surface of the insulator, and decreases with the growth of dry band width along the axial direction on the surface of the insulator. The increase of dry band number will decrease the electric field reciprocally.