Breakdown characteristics of CF3I and CF3I/N2 gas mixtures in uniform field

With its high insulation capability and excellent environmental friendliness, CF
₃
I has been considered as a potential substitute to SF
₆
. However, considering its high boiling point, CF
₃
I should be mixed with buffer gases such as CO
₂
or N
₂
. In this paper, breakdown performance of CF
₃
I/N
₂
gas mixtures, SF
₆
/N
₂
gas mixtures and pure SF
₆
gas in uniform field are investigated, with negative dc voltage or negative lightning impulse voltage applying. DC breakdown experiments of pure CF
₃
I gas and pure SF
₆
gas show that the dielectric strength of CF
₃
I is not always higher than that of SF
₆
. The insulation experimental results show that in low pressures, 30%CF
₃
I/70%N
₂
gas mixtures present similar insulation properties as 20%SF
₆
/80%N
₂
gas mixtures. Considering liquefaction temperature and insulation properties, 30%CF
₃
I/70%N
₂
gas mixtures could be possible substitutes to SF
₆
or SF
₆
/N
₂
gas mixtures in low pressures, and it is significant to study their insulation strength in higher pressures.