Effect of pollution layer discontinuity due to the dry bands presence on potential and electric field along insulator

This paper aims to study the effect of the presence of dry bands on the distribution of the electric field and potential on high voltage polluted insulator model subjected to impulse voltage. To take account of the influence of pollution thickness 3D computations were achieved with COMSOL Multiphysics Software. This Software uses Finite Element Method. The results of the simulation demonstrated that in presence of dry band, the electric field distribution is affected and becomes distorted along the surface of the polluted insulator. Numerical simulation showed also that the dry bands near the electrodes are responsible for more critical voltage and field stresses than in the case of a continuous pollution layer. It was observed extremely high stresses at the dry bands. The intensity of the electric field depends on the location and the width of dry bands.It was also observed that the potential grading can be improved by increasing the number of dry bands.