Dielectric breakdown properties of CF3I-N2 mixtures containing a small amount of SF6

Abstract

CF3I-N2 mixtures have garnered much attention as potential SF6-substitutes due to their excellent dielectric strengths, and the dielectric strength of SF6-N2 mixtures has a good synergy effect. This paper attempts to propose an approach of adding a small amount of SF6 to improve the dielectric strength of the CF3I-N2 mixture, by making an all-around consideration of dielectric strength, impact on the environment and the limitations of engineering pressure and the lowest ambient temperature. The influences of adding different amounts of SF6 on the electron energy distribution function, the reduced ionization, attachment and effective ionization coefficients, the critical reduced electric field strength and critical electron temperature of ternary SF6-CF3I-N2 mixtures are investigated by Boltzmann analysis. Then the relations of the critical electric fiend strength, mixed ratio and saturated vapor pressure of the ternary SF6-CF3I-N2 mixture are built and analyzed. The results demonstrate that an effective improvement of its dielectric strength can be obtained by adding a small amount of SF6 into the CF3I-N2 mixture, and that a proper choice of the mixed ratio and the gas pressure of the ternary SF6-CF3I-N2 mixture can provide a comparable dielectric strength to pure SF6.

Compatibility of Environmentally Friendly Insulating Gases CF3I and c-C4F8 with Cu Contacts

“…An environmentally friendly insulating gas to replace SF 6 has been developed. It is of great signi cance for alleviating environmental pollution, slowing global warming and industrial applications [4]. In recent years, environmentally friendly insulating media, such as C 5 F 10 O, C 4 F 7 N, CF 3 I, and c-C 4 F 8 produced by 3M Company in the United States attracted widespread attention.…”

“…In recent years, environmentally friendly insulating media, such as C 5 F 10 O, C 4 F 7 N, CF 3 I, and c-C 4 F 8 produced by 3M Company in the United States attracted widespread attention. A large number of domestic and foreign scholars have carried out related research on these gases [4][5][6][7][8][9]. Zhang et al [5] studied the decomposition mechanism of C 3 F 7 CN/CO 2 mixed gas.…”

Electron swarm coefficients and critical field strength of the gaseous ternary mixtures CF3I-SF6-N2 and CF3I-SF6-CO2

“…A promising approach to reduce the emission of SF 6 has been to dilute it with low GWP gases such as CO 2 [19][20][21], N 2 [11,22,23], N 2 O [24,25], CF 3 I [26,27] and HFO1234ze(E) (C 3 H 2 F 4 ) [28]. The mixture of SF 6 with N 2 is used to effectively reduce the proportion of high-energy electrons through vibrational excitation for electron energies between 2 and 3 eV, thereby favoring low-energy electron attachment [23,29]. One parameter of importance to assess the ability of a pure gas or gas mixture as a candidate for high voltage insulation is the critical or limiting field strength, E/N crit , defined as the E/N value for which the electron impact ionization and attachment coefficients of the gas or gas mixture are equal.…”