Reduction of electrical tree propagation in composite insulation using double barriering technique

In this paper, the impact of barriers on reducing tree growth was experimentally studied. An advanced optical system was employed to monitor and record the tree development in three types of samples: pure polyester resin, composite with one barrier and composite with two barriers of glass fiber. The tree growth was regularly measured and the images were digitally stored. The tree images were analyzed for different growth rates and time delays at the barriers. The tree characteristics were specified in each stage of growth from inception phase to the final breakdown. The relationship between the delay in tree growth and the number of barriers was determined for all samples. The tree growth in pure polyester resin samples was used as a reference for comparison purposes. Finally, the impact of barriers on shaping electrical trees was also discussed.