PERFORMANCE OF ROD-ROD GAPS IN THE PRESENCE OF DUST PARTICLES UNDER STANDARD SWITCHING IMPULSES

This paper presents the effects of simulated dust pollution on the bre akdown characteristics of protective gaps subjected to standard switch ing impulses (250/2500 mus) of both polarities. Hemispherical and squa re cut rod gaps were employed and their performance was compared in a gap spacing varying from 5 cm to 120 cm. It was found that dust pollut ion either reduces the 50% breakdown voltage or increases it, dependin g upon the gap spacing. Formation of a stable dust particle film on th e cathode was found to control these irregularities in breakdown param eters. It was also found that square cut rod gaps display immunity tow ard dust pollution under positive switching impulses and are therefore best suited for applications in terrains where dust storms are common .