Influence of nano and microparticles on the development of electrical trees

This paper deals with the effect of inorganic micro/nanofillers on electrical tree growth in high voltage insulation during application of AC voltage of 20 kV, 50 Hz. Pure epoxy samples were subject of experiment as well as epoxy micro/nanocomposites with hydrophobic nanosilica or hydrophilic microsilica. The times to breakdown were evaluated and compared. A transparent resin was used allowing observation of electrical tree grow with the help of an optical microscopes. Also the X-ray computed tomography was used for the 3D visualization of electrical trees in evaluated samples. The results show that the time required for the tree development and breakdown increases when a nanofiller or a microfiller is used. The tree growth optical patterns are different for pure epoxy, epoxy microcomposites and epoxy nanocomposites. The possible reasons why and how nanoparticles prolongs the time to breakdowns is discussed.