Surface Flashover Characteristics of the 252kV Conical Insulator in C4F7N/CO2 Gas Mixtures under AC Voltage
Li Zhichuang1, Zheng Zhongbo1, Liu Yishu2, Ding Weidong1, Li Xinyi3
1. State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong University Xi’an 710049 China;; 2. State Grid Chengdu Power Supply Company Chengdu 610000 China; 3. Xi’an XD Switchgear Electric Co. Ltd Xi’an 710077 China;
Abstract Developing alternatives to SF6 and investigating its feasibility of application to gas-insulated equipment have become one of the hot spots in the field of electrical engineering in recent years. C4F7N is an environment-friendly insulating gas with low global warming potential and excellent insulation performance, its mixtures with CO2 are expected to completely replace SF6. In this paper, the power frequency voltage withstand and surface flashover characteristics of 252kV conical insulators are studied in mixed gases with C4F7N content of 5%, 9% and 13%, and compared with the test results in 0.5MPa SF6. It is shown that most flashovers along the surface occur on the concave side of the insulator rather than on the convex side. The surface flashover voltage of C4F7N/CO2 mixture increases with the increase of gas pressure. Under the same gas pressure, the surface flashover voltage increases as the content of C4F7N in gas mixture increases, and there is a saturation trend. The flashover voltage of insulators in the 9% C4F7N/91% CO2 gas mixture under 0.6MPa is approximately equal to that in SF6 under 0.5MPa. The design criteria of the electrical field strength is given based on the experimental results.
Li Zhichuang,Zheng Zhongbo,Liu Yishu等. Surface Flashover Characteristics of the 252kV Conical Insulator in C4F7N/CO2 Gas Mixtures under AC Voltage[J]. Transactions of China Electrotechnical Society, 2020, 35(1): 62-69.
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2020, Vol. 35 
