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

Single and multiple rod gaps are uscd for overvoltage protection of various powcr system apparatus. Thesc are mostly located outdoors and are subjected to particulate contamination in desert lands. This paper discusscs the influence of pollution on thc breakdown voltage and breakdown time of protectivc air gaps. The rod radius and its end profile arc changed to find the configuration which is lcast affected by pollution. In addition practical protectivc gaps used across transformer bushings are tested to chcck their performancc in clcan and polluted conditions, It is found that such pollution drastically changes the gaps pcrformance. Specific recommendations are made regarding the choicc of suitablc protective rod gap configuration for arid rcgions.