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

Abstract

Member SF 6 has been identified as a greenhouse gas with a long atmospheric lifetime. In the long term, it is preferable to reduce the amount of SF 6 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 (N 2 ), and carbon dioxide (CO 2 ), are promising environmentally friendly candidates. In this paper, we describe the basic insulation characteristics of N 2 and CO 2 in the high-pressure range of up to 2.0 MPa 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 SF 6 . Moreover, we discuss the estimation of the cross-sectional size of a gas-insulated apparatus using high-pressure N 2 or CO 2 , based on insulation and thermal designs.

Synergy Effect in Electrical Insulation Characteristics of N₂O Gas Mixtures

“…In this paper, we newly focused on N 2 O gas as a promising insulating gas from the viewpoint of electron attachment ability as well as low GWP (GWP = 320). We also expected the synergistic effect on dielectric characteristics of N 2 O/CO 2 and N 2 O/CO 2 /O 2 gas mixtures with electron attachment ability at different electron energy levels; N 2 O, CO 2 and O 2 gases have the electron attachment cross section at 0.5∼4.0 eV, 6∼10 eV and 4.5∼8 eV respectively. Therefore, N 2 O/CO 2 and N 2 O/CO 2 /O 2 gas mixtures are expected to attach electrons with wide-range of energy and suppress the discharge propagation.…”

Insulation Characteristics of CO₂ Gas for Non-standard Lightning Impulse Oscillations

“…The actual lightning surge waveform (called non-standard lightning impulse waveform) is different from the standard lightning impulse waveform (1.2/50 µs), and the insulation requirements are not as severe as those of the standard lightning impulse waveform. Since SF 6 gas was identified as a greenhouse gas at COP3 in 1997, alternative insulation gases to SF 6 have been investigated. The CO 2 gas insulation is one of the candidates, which is a natural gas and has lower global warming potential (GWP).…”