The sensitivity of C 4 F 7 N to electric field and its influence to environment-friendly insulating gas mixture C 4 F 7 N/CO 2

Abstract C 4 F 7 N has excellent insulation performance. By mixing with CO 2 , it is the highest potential alternative gas to the most greenhouse effect gas insulating medium SF 6 , which is widely used in gas insulated high voltage electrical equipment. It is necessary to explore its insulation stability under different electrical fields before application. In this paper, the influence of electric field on C 4 F 7 N/CO 2 mixture with different gas pressures and mixing ratios is tested, analyzed and compared with SF 6 by experiment and calculation. It was found that the electric field sensitivity of C 4 F 7 N/CO 2 gas mixture is much higher than that of SF 6 and CO 2 , where it is easy for partial discharge to emerge under non-uniform electric field. The insulation performance of C 4 F 7 N/CO 2 gas mixture is extremely susceptible to the internal electric field of electrical equipment, and optimization of the equipment internal structure to avoid uneven electric fields is needed.