Influence regularity of O <sub>2</sub> on dielectric and decomposition properties of C <sub>4</sub> F <sub>7</sub> N–CO <sub>2</sub> –O <sub>2</sub> gas mixture for medium‐voltage equipment
Yi Li, Xiaoxing Zhang, Fanchao Ye, Dachang Chen, Shuangshuang Tian, Zhaolun Cui
Abstract
Fluorinated nitrile (C 4 F 7 N) gas mixture has been introduced as the mostpromising candidate to replace sulfur hexafluoride using in gas‐insulatedequipment. In this study, the authors explored the influence of oxygen on thedielectric and decomposition properties of C 4 F 7 N–CO 2 –O 2 gas mixture. Theauthors found that the dielectric strength of the C 4 F 7 N–CO 2 –O 2 gas mixture with 2,4, 6, 8 and 10% O 2 was increased by 4.85%, 6.49%, 7.70%, 3.21% and2.74% compared with C 4 F 7 N–CO 2 . The addition of2–6% O 2 to the C 4 F 7 N–CO 2 gas mixturecould effectively reduce the content of most of the decomposition by‐productssuch as CF 4 , CO, C 2 F 6 ,C 3 F 6 , C 3 F 8 , CF 3 CN,C 2 F 5 CN, (CN) 2 . While high content of oxygen(>6%) results in higher decomposition of C 4 F 7 N, whichhas a negative effect on the stability of C 4 F 7 N gasmixture. Generally, it is recommended to add 2–6% O 2 in the C 4 F 7 N–CO 2 gas mixture to improve itsinsulation properties as well as inhibit the decomposition of C 4 F 7 N in the discharge for medium‐voltage engineeringapplication.