BTF interruption capability of CF3I-CO2 mixture

In our research, CF₃I which has a low environmental impact was investigated as a substitute gas for SF₆. Global warming potential of CF₃I is less than 5 and the ozone depleting potential is near to zero. Additionally, CF₃I has a dielectric strength that is higher than SF₆. But, pure CF₃I application to gas insulated switchgear (GIS) or gas circuit breakers (GCB) is difficult because the liquefying temperature of the gas is high. Therefore, we mixed CF₃I with CO₂ to obtain a lower liquefying temperature, and have investigated the mixture gas. Consequently, the short line fault (SLF) interruption performance of CF₃I-CO₂(30%-70%) at upstream pressure of 0.2MPa(abs) was about 0.90 times that of SF₆. In this paper, we evaluated the breaker terminal fault (BTF) interruption capability which is important as well as SLF interruption performance for gas circuit breakers. The result showed that the BTF interruption performance of CF₃I-CO₂ (30%-70%) was about 0.67 times that of SF₆.