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

Investigations have been made to evaluate the performance of rod-rod gaps of two different shapes in the presence of simulated dust storms. Breakdown voltages and time lags have been determined for a range of gap spacings from 5 cm to 125 cm for standard lightning impulses. It was found: that the influence of particles in gap spacings of ⩾50 cm is small and is not of much practical importance, but in spacings <50 cm these have a marked effect as the positive breakdown voltage values are considerably reduced. An anomalous condition is reported for a 5 cm gap under negative polarity in which the 50% breakdown voltage is lower than the corresponding positive polarity value. It is shown that the breakdown values are not influenced by the airborne particles and the observed effects are due to the dust particles adhering to the cathode surface