Basic investigation of a macroscopic interface between two solid dielectrics

Most HV insulation systems consist of different insulating materials forming a composite insulation. In such systems, contact areas between dielectric components exist: the macroscopic interface is an area, which separates two solid insulating materials (for instance glass fibre reinforced epoxy versus the shed material). Due to interfacial polarisation phenomena and strength reduction in the dielectric border areas, the insulation behavior of composite systems may be greatly different from that of the single dielectric components. Therefore, both the electric and dielectric properties of macroscopic interfaces have been investigated. The breakdown voltage of specimen modelling such systems is influenced by prestresses like continuous ac voltages or humidity; for dry test samples a life time characteristic can be determined. Measurements of dielectric properties can be completed by calculations of interface characteristics dependent on different influences