Abstract
SF6 gas has been used for power apparatus as an insulation medium. Reduction of SF6 gas emission was discussed at COPS in 1997. It has been required to develop alternative gas apparatus as measures. This paper aims to acquire a sharp reduction in Global Warming Potential (GWP) of insulation gas without SF6 gas. In this paper, C3F8 was selected as an alternative gas and insulation characteristics of C3F8/N2, C3F8/CO2 and C3F8/CF4 gas mixtures were analyzed by Boltzmann equation. Furthermore, the experimental insulation characteristics of these gas mixtures for quasi-uniform electric field were obtained under ac voltage and were compared with analyses. As a result, analyses results corresponded to experimental results. All of insulation characteristics of tested gas mixtures had small synergism. Required gas pressures and GWP were discussed in comparison with those for SF6 gas and C3F8/N2 gas mixture had possibility of SF6 alternative gas in these gas mixtures.
