Study on Power Frequency Insulation Characteristics of CF3SO2F/C4F7N/N2 and CF3SO2F/C4F7N/CO2 Ternary Gas Mixture

SF
6
gas has high insulation strength, but SF
6
is a strong greenhouse gas, so it is necessary to study environmental protection insulating gas. CF
3
SO
2
F binary gas mixture with SF6 power frequency insulation strength at an absolute pressure of 0.5MPa has a high liquefaction temperature and cannot be directly applied to low temperature environment. Moreover, there are no reports on the study of its ternary gas mixture. To study the power frequency insulation characteristics of CF
3
SO
2
F/C
4
F7N/N
2
(CO
2
) ternary gas mixture, relevant data of its ternary gas mixture satisfying no liquefaction at -25°C are obtained through calculations and power frequency breakdown tests. The results show that when the gas mixture is at 20°C and the absolute pressure is 0.5MPa, the breakdown voltage of 20%CF
3
SO
2
F/6%C
4
F
7
N/74%N
2
reaches 1.05 times of SF6 and GWP is 9.43% of SF6; the power frequency breakdown voltage of 20%CF
3
SO
2
F/8%C
4
F
7
N/72%CO
2
is 1.07 times of SF6, GWP is 8.20% of SF
6
. At the same time, the results show that when the proportion of C4F7N increases by the same value, the power frequency breakdown voltage of the ternary gas mixture with a smaller proportion of C4F7N increases more obviously. When the proportion of C4F7N increases by the same value, the higher the air pressure is, the more obvious the increase effect is. Under the same mixing ratio and air pressure, the power frequency insulation strength of the ternary mixture of N2 is higher than that of the ternary mixture of CO2, and under the same air pressure, when the proportion of C4F7N increases by the same value, the power frequency breakdown voltage of the ternary mixture of CO
2
increases more obviously. The results of research and analysis can verify the feasibility of CF
3
SO
2
F/C
4
F
7
N/N
2
(CO
2
) ternary gas mixture and provide a basis for other ternary gas mixture research.