Influence of Lightning Impulse Breakdowns on the Surface of Plane Stainless Steel Electrodes

Inhalt:
With the new climate regulations concerning Sulphur hexafluoride (SF6) of the European Union, the demand to substitute SF6 as an insulating gas for high voltage switchgear is rising. In this paper, the influence of breakdowns at different levels of lightning impulse voltage on the surface of plane stainless steel electrodes is examined via a 4k microscope. An additionally examined parameter is the gap between the electrodes. The tests take place in an environment of an alternative gas mixture to SF6 and under increased pressure. The results show, that in relation to different levels of surface roughness of the observed electrodes, a smoother surface promotes the emergence of more significant micro protrusions. Further-more, a breakdown can also further smooth the existing surface in some cases.