Influence of dust pollution on the switching impulse breakdown of sphere gaps

Abstract EN

This paper discusses the effect of dust contamination on the breakdown characteristics of sphere-sphere air gaps when subjected to standard switching impulses of both polarities.

Spheres having diameters (D) of 125 mm and 250 mm were used with d/D ratio (d = gap length) in the range of 0.2 to 1.5.

It is shown that, for gaps with 0.2 < d/D < 1, the dust pollution can reduce the 50% breakdown voltages (V50) and the scatter in breakdown voltages as well as in breakdown time lags for both polarities of impulse voltages.

For d/D > 1, the dust particles can increase ^50 values under some conditions.

It is further shown that for d/D < 0.5, the region where sphere gaps are used for voltage measurements, the influence of dust particles on breakdown characteristics is similar to the effect of ultraviolet irradiation.