The effect of fillers and barrier on electrical tree

This paper deals with the effect of inorganic micro/nanofillers and nanofabric on electrical tree growth in high voltage insulation. Experiments were conducted at a constant AC voltage of 20 kHz, 50 Hz epoxy samples without any fillers as well as epoxy nanocomposites with hydrophobic nanosilica or hydrophilic microsilica or polyamide nanofabric. The time to breakdown tree was observed and the transparency of the resin allows observe branches of electrical trees by the help of an electronic microscope. The results show that the time required for the tree to reach the opposite electrode increases, for a nanofiller and a microfiller loading of 1% by weight in comparison with unfilled epoxy. Polyamide nanofabric used as a barrier doesn't have influence for increased time to breakdown, only changes the direction of tree growth. The tree growth patterns are different for both the pure epoxy and the epoxy nanocomposites. The possible reasons why and how nanoparticles improve the electrical tree growth resistance are discussed.