The present binary mixtures of the SF6 gas with Ar and Kr gases have not been used in many industries as long-term measures for totally eliminating the potential contribution of SF6 to global warming. | ISSN 1859-1531 - THE UNIVERSITY OF DANANG, JOURNAL OF SCIENCE AND TECHNOLOGY, NO. 6(127).2018 17 A STUDY ON CF3I-Ar AND CF3I-Kr MIXTURE GASES SUBSTITUTING SF6 IN HIGH VOLTAGE EQUIPMENTS Tran Thanh Son1, Do Anh Tuan2 Electric Power University; sontt@ 2 Hung Yen University of Technology and Education; tuandoanh@ 1 Abstract - The present binary mixtures of the SF6 gas with Ar and Kr gases have not been used in many industries as long-term measures for totally eliminating the potential contribution of SF6 to global warming. In order to gain more insight into electron transport coefficients in mixture gases as substitutes for SF 6 in high voltage equipment, transport coefficients such as electron drift velocity, density-normalized longitudinal diffusion coefficient, ratio of the longitudinal diffusion coefficient to the electron mobility, Townsend first ionization coefficient, electron attachment coefficient, and density-normalized effective ionization coefficient in CF 3I-Ar and CF3I-Kr mixture gases are calculated and analyzed in the wide E/N range of – 1000 Td using a two-term approximation of the Boltzmann equation for the energy. These calculated coefficients are analyzed and compared to those in pure SF 6 gas. The limiting field strength values of E/N, (E/N)lim, of these mixture gases are also derived and compared with those of the pure SF 6 gas at different percentages of CF 3I and SF6. The mixture gases of 70% CF3I with Ar and Kr have (E/N)lim values greater than those of the pure SF 6 gas. Therefore, these mixture gases could be considered to substitute SF6 gas in high voltage equipment. Key words - Trifluoroiodomethane; CF3I; SF6; Boltzmann equation analysis; electron transport coefficients; gas mixture 1. Introduction Sulfur hexafluoride (SF6) has been widely used as an isolated gas in high voltage equipment. The Kyoto Protocol, however, has listed the greenhouse gases as CO2, CH4, N2O, hydrofluorocarbons (HFCs), .
