Lightning Impulse Breakdown Characteristics in Compressed N₂ and CO₂ and Feasibility of their Gases' Application to Gas-Insulated Buses

抄録

SF₆ has been identified as a greenhouse gas with a long atmospheric lifetime. In the long term, it is preferable to reduce the amount of SF₆ used. Therefore, it is important to discuss the possibility of using environmentally friendly gases as alternative insulation gases for practical gas-insulated apparatuses. In the selection of an alternative gas, it is thought that high-pressure natural gases, such as air, nitrogen (N₂), and carbon dioxide (CO₂), are promising environmentally friendly candidates. In this paper, we describe the basic insulation characteristics of N₂ and CO₂ in the high-pressure range of up to 2.0MPa under a quasi-uniform electric-field gap and under a non-uniform one in the presence of a metallic particle, and the characteristics are compared with those of SF₆. Moreover, we discuss the estimation of the cross-sectional size of a gas-insulated apparatus using high-pressure N₂ or CO₂, based on insulation and thermal designs.