Breakdown characteristics of [N.sub.2]O gas mixtures for quasi-uniform electric field under lightning impulse voltage

From the viewpoint of mitigating global warming by S[F.sub.6] gas, this paper discusses breakdown (BD) characteristics of different electronegative gas mixtures with [N.sub.2]O gas as S[F.sub.6] gas substitutes for quasi-uniform electric field under lightning impulse voltage applications. Experimental results revealed the positive synergism in breakdown strength of binary [N.sub.2].O/C[O.sub.2] and ternary [N.sub.2].O/C[O.sub.2]/[O.sub.2] gas mixtures, respectively. Furthermore, [N.sub.2] gas as a retardant gas was also mixed with the electronegative gas mixtures in order to reduce the electron energy into the effective levels of electron attachment ability by the electronegative gas mixtures. As the result, ternary [N.sub.2].O/ C[O.sub.2] / [N.sub.2] and quaternary [N.sub.2].O / C[O.sub.2] / [O.sub.2] / [N.sub.2] gas mixtures could exhibit the significant synergistic effect in breakdown strength. The optimum mixture rate of quaternary [N.sub.2].O /C[O.sub.2]/[O.sub.2]/[N.sub.2] gas mixtures was consistent with that estimated by assuming the independent contribution of component gases to the improvement of impulse BD characteristics. Index Terms--GIS, impulse breakdown, [N.sub.2].O gas, S[F.sub.6] substitutes.