Discharge development in the layered dielectrics

The results of experimental and computer investigations of the discharge development features in the three-layered isolation systems under conditions similar to uniform external field are presented. The influence of the relationship between dielectric permittivities of a basic dielectric (ε_d) and barrier (ε_b) as well as position of the layer interfaces (r) on the spatial-time discharge characteristics is studied. For computer investigations a fractal dielectric breakdown model is used. The space charges resulted from differences in layer dielectric permittivities are shown to induce the electric field redistribution, which has an essential influence on the character of the discharge structure development. At εd/εb>3 field redistribution is quite enough to cause the effects of keeping back the discharge channels in a barrier layer. This is more efficient at r≈0.25. In this case a maximum increase in time, until the three-layered isolation systems are broken, is observed.