Comparison of the performance of silicone and glass barriers under direct current and very severe conditions of pollution

The main objective of this paper consists in the comparison of the performance in DC voltage of a short air gap with non-uniform electrical field protected by silicone or glass barriers under very severe conditions of pollution. The choice of the investigation system is related to the rod and plane electrodes. The essential influence parameters on the performance of the system are summarized in the severity of the level of pollution of the barrier and the orientation of the axis of the basic electrodes of the system. These tests were supported by a visualization of the breakdown path followed by the electrical discharge on the barrier. An experimental device allowing simultaneously the orientation of the axis of the electrodes and the displacement of the barrier inside the air gap was made. The results show that under pollution conditions, the effective electrical protection offered by the silicone barrier is highly efficient than the glass one. Under the effect of the contaminated water droplets, the system with vertical or horizontal silicone barrier, floating above the energized rod is more rigid than when this silicone barrier is horizontal, and located below the energized electrode. The quantification of the voltages decrease is made possible by a mathematical model.