Discharge development in layered dielectrics

The results of experimental and computer investigation of discharge development features in three-layer insulation systems under conditions similar to a uniform external field are given. The influence of the relationship between the dielectric permittivity of a basic dielectric (ε_d) and barrier (ε_b) as well as the position of the layer interfaces (r) on the space-time discharge characteristics is studied. For computer investigation, a fractal dielectric breakdown model is used. The space charges resulting from differences in layer dielectric permittivity are shown to induce an electric field distribution, which has a significant influence on the character of the discharge structure development. For ε_d ε_b > 3, field redistribution is sufficient to cause holding of discharge channels in the barrier layer. This is more efficient at r ≈ 0.25. In this case the maximum increase in time before the three-layer insulation systems are broken down is observed.