AC breakdown characteristics of CF3I/N2 in a non-uniform electric field

CF
₃
I and mixed gases containing CF
₃
I are potential substitutes of SF
₆
in electrical equipment. In this paper, we studied the feasibility of replacing SF
₆
with CF
₃
I/N
₂
in terms of power frequency breakdown performance under the influence of gas pressure, mixing ratio, and electric field. The synergistic effect, liquefaction temperature, and self-recover ability of CF
₃
I/N
₂
were analyzed. Experimental results showed that, under a highly uniform electric field, the sensitivity of the power frequency breakdown characteristics of the gases to pressure shows the order SF
₆
CF
₃
IN
₂
. The power frequency AC breakdown strength of CF
₃
I/N
₂
(30%/70%) at electrode distances of 5 and 10 mm could reach over 0.9 and 0.85 times that of SF
₆
at 0.3 MPa, respectively. CF
₃
I/N
₂
showed positive synergistic effects and the improvement was attributed to N
₂
. CF
₃
I presents excellent self-recoverability. The optimum ratio of CF
₃
I/N
₂
to replace SF
₆
gas as insulating medium is 30% at 0.3 MPa.