Sparkover in the conductor-rod and conductor-plane test gaps under composite slow front impulse/direct voltages

Measurements of sparkover voltages and of corona in 0.5 and 0.8 m conductor-rod and conductor-plane gaps are described. Where positive pre-stress voltages are used, sufficiently great to produce corona, significant increases in positive composite sparkover voltages are found in the conductor-rod gap, but effects in the conductor-plane gap are insignificant. Sparkover voltage variations are discussed in terms of corona measurements made in the same series of experiments; it is concluded that corona from the rod is dominant in determining conditions for breakdown