We studied the interruption performance of CF{sub}3I gas because its environmental effect is smaller than that of SF{sub}6 gas with a model arc-extinguishing chamber. First, we measured the arc time constant and arc power loss coefficient using Mayr's equation. Comparing CF{sub}3I with other gases, the arc time constants are SF{sub}6 SF{sub}6 > CO{sub}2 > Air > N{sub}2 > CF{sub}3I. Next, we evaluated the Short Line Fault (SLF) interruption capability by measuring the di/dt-dv/dt characteristic. Consequently, the SLF interruption performance of pure CF{sub}3I was about 0.9 times that of SF{sub}6. However, CF{sub}3I application to gas insulated switchgear (GIS) and gas circuit breakers (GCB) is difficult because the liquefying temperature of the gas is high. Therefore, we adopted a countermeasure to obtain a lower liquefying temperature mixing CF{sub}3I with CO{sub}2. The result showed that the SLF interruption performance of the mixture approximated that of pure CF{sub}3I when the ratio of CF{sub}3I exceeds 20.
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