Basic electrical characteristics of epoxy/hollow silica composites influenced by addition of hollow silica

Polymeric insulating materials like an epoxy resin due to their excellent electric performance and a maintenance performance are commonly applied to various power equipment. Additives and fillers are traditionally added into the epoxy resin to improve the mechanical and thermal properties. The epoxy/hollow particle composites have been developed to produce the composite material which has new function like the low dielectric constant, the lightweight, and the high heat insulation. To understand the basic electrical properties of epoxy/hollow silica composites, the capacitance measurement, the breakdown test and the partial discharge measurements were performed. The breakdown strength of the epoxy/hollow silica composites and the breakdown strength of the epoxy/no hollow silica (normal silica) composites were almost the same regardless of the applied voltage waveform. The AC breakdown voltage at the 0‐peak of the epoxy/hollow silica composites also agreed with the DC breakdown voltage of that. Furthermore, the PDIV of the epoxy/hollow silica composites was almost the same compared to that of epoxy/normal silica composites. The continuous partial discharge in the hollow region did not cause the breakdown, and the existence of the interface between the silica particle and the epoxy resin might lead to the breakdown.