Performance of rod-rod gaps in the presence of dust particles under standard switching impulses

The effects of simulated dust pollution on the breakdown characteristics of protective gaps subjected to standard switching impulses (250/2500 mu s) of both polarities are presented. Hemispherical and square cut rod gaps are used, and their performance is compared in a gap spacing varying from 5 cm to 120 cm. It is found that dust pollution either reduces the 50% breakdown voltage or increases it, depending upon the gap spacing. Formation of a stable dust particle film on the cathode is found to control these irregularities in breakdown parameters. It is also found that square cut rod gaps display immunity toward dust pollution under positive switching impulses, and are therefore best suited for applications in terrains where dust storms are common.<>