Experimental study on the partial discharge and AC breakdown properties of C ₄ F ₇ N/CO ₂ mixture

Abstract

As an environmental friendly insulating medium, C 4 F 7 N has received extensive attention in the past two years. In this study, the partial discharge (PD) and breakdown characteristics of C 4 F 7 N/CO 2 gas mixture were investigated using the gas insulation performance test platform. The influence of gas pressure and mixing ratio on the PD initial voltage (PDIV) and breakdown voltage of C 4 F 7 N/CO 2 gas mixture in different electric fields was tested. It was found that the PDIV and breakdown voltage of gas mixture with 2–8% C 4 F 7 N in the highly non‐uniform field showed a linear saturation increasing trend with the change of gas pressure and mixing ratio. The breakdown voltage of gas mixture increases linearly with gas pressure in the quasi‐uniform electric field. The relative breakdown voltage of gas mixture in the highly non‐uniform field under high‐pressure conditions is inferior to those of low‐pressure conditions. The C 4 F 7 N/CO 2 gas mixture containing 2–8% C 4 F 7 N is sensitive to the non‐uniformity of electric field. According to the PD and breakdown tests results, C 4 F 7 N/CO 2 gas mixture with 2–8% C 4 F 7 N has the potential to replace SF 6 using in gas‐insulated equipment.