Influence of humidity on the sparkover of rod-rod gaps of several geometrical forms subjected to positive impulse voltages of varying waveshapes

The humidity correction factor suggested in BS 923:1972 for sparkover under lightning and switching impulse voltages relates to rod-rod gaps; there is no suggestion that the factor might vary with the actual geometrical shape of the termination of the rods, with gap spacing or with waveshape of the applied impulse. Large variations of the correction factor have been found as each of these parameters is changed, and the observed values have been discussed in relation to the inception times of corona formation and times to sparkover of the gaps.