Comparative study on various dielectric barriers and their effect on breakdown voltage

Abstract

Non-pressurised air is extensively used as basic insulation medium in high-voltage equipment. Unfortunately, an inherent property of air-insulated design is that the system tends to become physically large. On the other hand, the application of dielectric barriers can increase the breakdown voltage and therefore decrease the size of the equipment. In this study, the impact of dielectric barriers on breakdown voltage enhancement is investigated under both direct current (dc) and alternating current (ac) applied voltages. For this purpose, three kinds of dielectric barriers in two different high-voltage electrode structures are investigated. In the first structure, several experiments are carried out with four different electrode arrangements, keeping the inter-electrode gap constant while varying the position of the dielectric barrier between the electrodes. In the second structure, the inter-electrode gap is varied while the high-voltage electrode is covered with dielectric materials. The influences of different parameters such as inter-electrode spacing, electric field non-uniformity factor, and dielectric materials on the breakdown voltage are investigated for applied 50 Hz ac and dc voltages. In addition, a simulation model to approximately calculate the breakdown voltage is proposed and validated with the experimental results.