Electric Tree Characteristics of Glass Fiber Reinforced Epoxy Insulation Composites with Different Contents

Abstract

Electric tree aging due to the action of long-term partial discharge stress of epoxy resin casting insulation is a major problem in electrical engineering. On the discharge experimental platform, initiation and culture experiments of the electric trees were carried out at a power frequency voltage of 20 kV. The mass fractions of the spherical glass fibers were 0, 0.5, 1, 2 and 3 %. The results showed that the electrical dendritic process of epoxy resin experienced initiation, growth, lag and burst periods, the phase maps of the corresponding partial discharges in the four periods were all “mountain-like”. The electric tree of pure epoxy resin showed a typical dendritic structure, after the glass fiber was properly added, the electric tree became lighter in color with a more complicated shape, the damage also became more serious, however, the growth of the electric branch was suppressed. The electric tree aging channel of the epoxy resin appeared black and under microscopy the micro-branched channel wall appeared white. When the amount of glass fiber was 2 %, the initiation time of the electric trees was prolonged, the growth rate of the electric trees decreased and suppressing development of the electric tree branches was optimal.