Performance of protective rod gaps for medium voltage networks in the presence of dust particles under lightning impulses

Single and multiple rod gaps are used for the overvoltage protection of various power system apparatus. These are mostly located outdoors and are subjected to particulate contamination in desert lands. This paper discusses the influence of pollution on the breakdown voltage and breakdown time of protective air gaps. The rod radius and its end profile are changed to find the configuration which is least affected by pollution. In addition, practical protective gaps used across transformer bushings are tested to check their performance in clean and polluted conditions. It is found that such pollution drastically changes the gaps performance. Specific recommendations are made regarding the choice of suitable protective rod gap configuration for arid regions