INFLUENCE OF DESERT POLLUTION ON THE LIGHTNING IMPULSE BREAKDOWN VOLTAGES OF ROD TO PLANE AIR GAPS

This paper discusses the influence of desert contamination on the breakdown voltage characteristics of rod-plane air gaps when subjected to standard lightning impulse voltages of positive and negative polarities. Experimental simulation of desert air pollution was carried out in a chamber where particle parameters could be controlled independently. The gaps studies were from 5 cm up to 2 m with applied voltages of up to 1 MV. The results indicate that there is a little change in the breakdown voltages due to the presence of sand/dust pollution for positive lightning impulse voltages. However, for negative impulse voltages, there is a considerable influence on the breakdown behaviour. For such cases, the breakdown voltages for dust contaminated gaps can be lower as well as higher than the corresponding values for the clean air gaps depending upon the gap length and the cathode radius. The paper provides detailed results and analysis of the studies.