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

摘要

CF3I and mixed gases containing CF3I are potential substitutes of SF6 in electrical equipment. In this paper, we studied the feasibility of replacing SF6 with CF3I/N2 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 CF3I/N2 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 SF6CF3IN2. The power frequency AC breakdown strength of CF3I/N2 (30%/70%) at electrode distances of 5 and 10 mm could reach over 0.9 and 0.85 times that of SF6 at 0.3 MPa, respectively. CF3I/N2 showed positive synergistic effects and the improvement was attributed to N2. CF3I presents excellent self-recoverability. The optimum ratio of CF3I/N2 to replace SF6 gas as insulating medium is 30% at 0.3 MPa.