Abstract:
This research studies the effect of electrode type and the ratio of absolute humidity to the air density
on positive DC breakdown voltage of air - gap under atmospheric conditions. Test electrodes were
made of copper, brass and aluminum. Test gap configurations were sharp ended rod - plane, sharp
ended rod - sharp ended rod and hemispherical ended rod - hemispherical ended rod. The sharp
ended rods have the length of 20 ern with 4 different tip angles, 15 ํ, 30 ํ, 45 ํ and 60 ํ. The plane
sizes were 4*4*2 cm3 and 20*20*1 ern'. The radius of the hemispherical tip was 1 cm, They were
tested under gap length of 2-12 em with the ratio of absolute humidity to the air density of 9-22 g/m3
Results of breakdown voltage at the same condition were compared. The results show that the
breakdown voltage increases as the ratio of absolute humidity to the air density increases.
Furthermore, the brass electrode has the highest breakdown voltage followed by copper electrode
while the aluminum electrode has the lowest breakdown voltage.