LAUSR

As a new environmental-friendly gas insulating medium, perfluoroisobutyronitrile (C₄F₇N) has been widely concerned in recent years due to its relatively low global warming potential and excellent dielectric strength, which has the potential to replace the most greenhouse gas, sulfur hexafluoride(SF₆). However, there are a few systematic studies on the influence of gas pressure and mixing ratio on the dielectric strength of C₄F₇N/CO₂ gas mixture at present. In this paper, the power frequency breakdown characteristics of C₄F₇N/CO₂ gas mixture under different pressure and mixing ratio conditions were tested using the gas insulation performance test platform. The optimal mixing ratio and pressure range of C₄F₇N/CO₂ gas mixture for engineering application were also discussed. It is found that the breakdown voltages of C₄F₇N/CO₂ gas mixture show a saturated growth trend with gas pressure and mixing ratio. The breakdown voltage of the gas mixture with 10% C₄F₇N can reach 80% of pure SF₆ under the same condition. The insulation performance of the gas mixture with 20% C₄F₇N can reach more than 95% of pure SF₆. Relevant results indicate that the gas mixture with 4%–12% C₄F₇N has the potential to be applied to high-voltage gas-insulated equipment.