Experimental study of breakdown voltage-time characteristics of large air gaps with lightning impulses

This study reports mainly two points about the breakdown voltage - time characteristics of 1 - 5 m rod-plane and rod - rod gaps with lightning impulses. It is shown, at first, that the breakdown time follows the logarithmic normal distribution with a constant impulse level and that the probability of the breakdown time can be determined by empirical equation from the mean breakdown time and its standard deviation. The second part covers the breakdown phenomena with lightning impulses, delineating the development of streamers and leaders in relation to breakdown time. Estimates on basis of breakdown processes are made to breakdown time with impulses of short tail waves.