Space Charge Accumulation and DC Breakdown Strength of Epoxy Nanocomposites

Introduction of inorganic nanoparticles to epoxy composite material has been demonstrated to have a significant advantage in electrical insulation performance for use in power apparatus. In order to apply nanocomposites to solid insulators in DC power equipment, it is important to evaluate the electrical insulation properties of nanocomposites under DC high voltage. It is well understood that space charges accumulating inside insulating materials can lead to premature failure. In this work, the space charge and DC breakdown of epoxy nanocomposites with nano-BN or TiO2 were investigated. The space charge accumulation can locally increase the effective electric field strength in a region of the insulator and thus leads to a dielectric breakdown. It was previously demonstrated that specific types of nanocomposites can reduce space charge accumulation. The nanocomposites prepared in this study do not suppress space charge accumulation, which could be due to the presence of micrometric-size agglomerates in the nanocomposites prepared in this study. Furthermore, the effect of the agglomerates on space charge accumulation and DC breakdown strength depends on the nanofiller.