DISCHARGE DEVELOPMENT IN LAYERED DIELECTRICS

The results of experimental and computer investigation of discharge de velopment features in three-layer insulation systems under conditions similar to a uniform external field are given. The influence of the re lationship between the dielectric permittivity of a basic dielectric ( epsilon(d)) and barrier (epsilon(b)) as well as the position of the la yer interfaces (r) on the space-time discharge characteristics is stud ied. For computer investigation, a fractal dielectric breakdown model is used. The space charges resulting from differences in layer dielect ric permittivity are shown to induce an electric field distribution, w hich has a significant influence on the character bf the discharge str ucture development. For epsilon(d)/epsilon(b) > 3, field redistributio n is sufficient to cause holding of discharge channels in the barrier layer. This is more efficient at r approximate to 0.25. In this case t he maximum increase in time before the three-layer insulation systems are broken down is observed.