Breakdown Characteristics of Eco-friendly Gas for Live Tank Multi-break Vacuum Circuit Breakers

Insulation properties of environment-friendly gas have been widely concerned in recent years. However, breakdown characteristics of environment-friendly gas for live tank multi-break vacuum circuit breakers have not been fully understood at present. In this paper, the structure of environment-friendly live tank multi-break vacuum circuit breakers is proposed, and the electric field simulation is operated to gain the electric field distribution and dielectric weakness. Then, the breakdown tests of dry air under various electrode structures and gas pressures are conducted through gas insulation characteristics experimental platform. The effects of gas pressure and electrodes distance on the breakdown voltage are analyzed under various electrodes structures. The result shows that the breakdown voltage increases with the increasing gas pressures and electrodes distance in general, although there is saturation effect. Under the same condition except electrodes structures in AC breakdown voltage, the dielectric strength comparison is plate-plate > ball-plate > coaxial > needle-plate. In DC breakdown voltage, there is more stable various trend and less fluctuation in positive DC breakdown data. The positive and negative DC breakdown voltage of needle-plate electrodes shows the opposite trend before and after 15 mm distance. The positive DC breakdown voltage is higher than negative DC breakdown voltage in other electrodes. The results can provide a reference for insulation design for environment-friendly gas insulation equipment.