Investigation of the performance of CF₃I/c-C₄F₈/N₂ and CF₃I/c-C₄F₈/CO₂ gas mixtures from electron transport parameters

CF₃I gas mixtures have attracted considerable attention as potential environmentally-friendly alternatives to SF₆ gas, owing to their excellent insulating performance. This paper attempts to study the CF₃I ternary gas mixtures with c-C₄F₈ and buffer gases N₂ and CO₂ by considering dielectric strength from electron transport parameters based on the Boltzmann method and synergistic effect analysis, compared with SF₆ gas mixtures. The results confirm that the critical electric field strength of CF₃I/c-C₄F₈/70 % CO₂ is greater than that of 30% SF₆/70% CO₂ when the CF₃I content is greater than 17%. Moreover, a higher content of c-C₄F₈ decreases the sensitivity of gas mixtures to an electric field, and this phenomenon is more obvious in CF₃I/c-C₄F₈/CO₂ gas mixtures. The synergistic effects for CF₃I/c-C₄F₈/70 % N₂ were most obvious when the c-C₄F₈ content was approximately 20%, and for CF₃I/c-C₄F₈/70 % CO₂ when the c-C₄F₈ content was approximately 10%. On the basis of this research, CF₃I/c-C₄F₈/70 % N₂ shows better insulation performance when the c-C₄F₈ content is in the 15%–20% range. For CF₃I/c-C₄F₈/70 % CO₂, when the c-C₄F₈ content is in the 10%–15% range, the gas mixtures have excellent performance. Hence, these gas systems might be used as alternative gas mixtures to SF₆ in high-voltage equipment. (paper)