Dielectric characteristics of SF/sub 6/ under the steep-fronted impulses

The influence of the wavefront duration on impulse breakdown voltage of the nonuniform field gap in compressed SF/sub 6/ gas has been studied using a point-plane electrode arrangement. Voltage-time curves are also given in this paper. For comparison purposes, dielectric characteristics of SF/sub 6/ in a sphere-plane gap have been measured. The wavefronts used in this work are 0.05, 0.3, 0.6, 0.9, 1.2 and 1.5 /spl mu/s. The experimental results show that the wavefront duration has significant influence on the dielectric behaviour of SF/sub 6/ in the nonuniform field. It is found that the breakdown voltage-wavefront relationships and voltage-time curves of nonuniform field tend to be U-shaped.