Interfacial charge behaviour at dielectric - dielectric interfaces

Multi-dielectric insulation systems are commonly used in high voltage apparatus. Interfacial charge accumulated at the dielectric - dielectric interface governs the dielectric behaviour of the composites considerably. In this work, we perform space charge measurements on polymeric composites of epoxy resin and polyethylene, to investigate the behaviour of interfacial charge at the interfaces, under various experimental conditions. Pulsed Electro-Acoustic (PEA) system is used for measurement of charge distribution. The interfacial charge at the discontinuities, in similar as well as dissimilar dielectrics, is studied. Interfacial charge is seen to develop at discontinuities within otherwise homogeneous materials. Accumulation of space charge above threshold fields, at interfaces of different materials, ultimately dominates the polarity and magnitude of accumulated charge.