Computation of electrostatic field around a partially wet insulator surface through numerical techniques and simulation

Insulators in actual service conditions are polluted due to ambient operating conditions. Due to leakage currents dry bands can be formed on the surface of the insulators. Distortion of the potentials would occur by the existence of both a wet polluted band and a dry band in presence of air. In this work a rotationally symmetric approximation of the insulator is considered with varying lengths of dry band and wet bands. Simulations are carried out with different values of resistivities for wet and dry bands and different ratios of wet and dry band dimensions. Finite difference code was developed to calculate the potential & stress distributions. Two configurations were considered. In one the dry band is maintained next to high voltage electrode and in the other dry band is maintained next to grounded electrode. The details of simulation, the configurations considered our results and conclusions are presented.