高气压下O_(2)对C_(4)F_(7)N/N_(2)混合气体绝缘性能和分解特性的影响

Effect of O_(2)on Insulation Performance and Decomposition Characteristic of C_(4)F_(7)N/N_(2)Gas Mixture at High Gas Pressure

由于SF_(6)的大量使用对环境产生的影响巨大,因此替代气体的研究受到了广泛关注。C_(4)F_(7)N混合气体具有优良的绝缘性能和环保特性,有望替代SF_(6)作为绝缘介质应用于气体绝缘设备中。为了减少放电过程中产生的有害固体副产物,需要在C_(4)F_(7)N/N_(2)混合气体中加入一定体积分数的O_(2)。文中探究了C_(4)F_(7)N/N_(2)/O_(2)混合气体应用于高气压电气设备的潜力,利用气体绝缘试验平台对0.6 MPa下含不同体积分数氧气的C_(4)F_(7)N/N_(2)/O_(2)混合气体开展击穿试验,同时利用气相色谱质谱联用仪(GC-MS)分析混合气体击穿后的分解产物及体积分数。研究发现在C_(4)F_(7)N/N_(2)混合气体中加入一定量的O_(2)可以提高混合气体在高气压下的绝缘自恢复性能,混合气体多次击穿后分解的主要产物有CF_(4)、C_(2)F_(6)、C_(3)F_(6、)C_(3)F_(8)、CF_(3)CN、C_(2)F_(5)CN、CO、COF_(2)、C_(2)N_(2)等,这些产物的体积分数随氧气体积分数的增加均呈先增加后减少的趋势。综合考虑O_(2)的添加量对C_(4)F_(7)N/N_(2)混合气体绝缘性能的影响和放电分解后产物的绝缘性能及毒性,C_(4)F_(7)N/N_(2)/O_(2)混合气体应用于高气压电气设备时,O_(2)的添加量为6%比较适合。

Since the significant influence on the environment by the large use of SF_(6),therefore,the study on alterna-tive gases has received extensive attention.C_(4)F_(7)N gas mixture has excellent insulation performance and environmen-tal protection characteristics and is expected as insulation medium to be alternative to SF_(6)and used in gas insulatedequipment.For reducing harmful solid by-products generated during discharge period,a certain amount of volumefraction of O_(2)needs to be added to the C_(4)F_(7)N/N_(2)gas mixture.In this paper,the application potential of C_(4)F_(7)N/N_(2)/O_(2)gas mixture in high voltage electrical equipment is explored.The gas insulation test platform is used to perform thebreakdown test of C_(4)F_(7)N/N_(2)/O_(2)gas mixture containing different volume fractions of oxygen at 0.6 MPa.At the sametime,the gas chromatography-mass spectrometry(GC-MS)is used to analyze the decomposition products and volumefraction of the gas mixture after breakdown.It is found by the study that adding a certain amount of O_(2)to C_(4)F_(7)N/N_(2)gas mixture can improve the insulating self-recovery performance of the gas mixture at high gas pressure.The maindecomposition products of the gas mixture after multiple breakdowns are CF_(4),C_(2)F_(6),C_(3)F_(6),C_(3)F_(8),CF_(3)CN,C_(2)F_(5)CN,CO,COF_(2),C2N_(2),etc.The volume fraction of those products shows the trend of firstly increase and then decrease with theincrease of oxygen volume fraction.Comprehensively considering the effect of added amount of O_(2)on the insulation performance of the C_(4)F_(7)N/N_(2)gas mixture and the insulation performance as well as and toxicity of the products afterdischarge and decomposition,it is concluded that 6%O_(2)is more suitable when C_(4)F_(7)N/N_(2)/O_(2)gas mixture is used inhigh voltage electrical equipment.