Interruption capability and decomposed gas density of CF3I as a substitute for SF6 gas

We investigated the fundamental characteristic of CF
₃
I as a substitute gas for SF
₆
. CF
₃
I has lower global warming potential. The use of pure CF
₃
I in gas-insulated switchgear and gas circuit breakers is difficult because liquid CF
₃
I has a high boiling point. We therefore mixed CF
₃
I with CO
₂
or N
₂
. In short line fault (SLF, 1 kA
_peak
) and breaker terminal fault (BTF, 3 kA
_peak
) interruption, the performance of CF
₃
I-CO
₂
approximated that of pure CF
₃
I when the proportion of CF
₃
I exceeded 30%. However, for BTF (20 kA
_peak
) interruption, the performance of CF
₃
I-CO
₂
remarkably decreased. In loop current interruption for disconnecting switches, CF
₃
I-CO
₂
(30%/70%) was successfully used 200 times for 4000 A. We also measured CF
₃
I spectra. Investigation of the decomposed gas density after current interruption revealed that fluorine release from CF
₃
I was less than that from SF
₆
. Iodine density released from CF
₃
I-CO
₂
(30%/70%) was approximately one-third of that released from pure CF
₃
I. In addition, iodine could be removed using an adsorbent.