The influence of interfaces and channels on electrical tree growth in epoxy resin

This experimental study sought to investigate the influence of interfaces and ventilated channels on electrical tree growth in epoxy resin. The electrical trees were developed in point-plane geometry samples and tested within the voltage range of 6 - 15 kV rms. Vented channels of diameters in the range 0.16 - 0.30 mm were employed. The distance to the grounded plane from both the epoxy resin interface and the ventilated channels varied between 0.5 - 1.5 mm. The time to breakdown is increased when the location of the interface and channels is centred near the insulation gap or is closer to the plane surface, but decreases when the interface is closer to the needle. A narrower breakdown path is observed when the interface layer is present.