CO<sub>2</sub>ガスの非標準雷インパルス振動波形に対する絶縁特性（その1）

Abstract

Since SF6 gas was identified as a greenhouse gas at COP3 in 1997, alternative insulation gases to SF6 have been investigated. The CO2 gas insulation is one of the candidates, which is a natural gas and has lower global warming potential (GWP). However, CO2 gas has a lower withstand voltage level than SF6; therefore, it is important to rationalize the equipment insulation level and reduce the test voltage of electric power equipment as low as possible. The actual lightning surge waveform (called non-standard lightning impulse waveform) in actual substations is different from the standard lightning impulse waveform (1.2/50μs). The actual lightning surge waveform generally rises steeply, however, the decay of the overvoltage is large, and the insulation requirements are not as severe as those of the standard lightning impulse waveform.This paper describes the insulation characteristics of CO2 gas for single-frequency oscillatory waveforms with various frequencies from 1.3 to 4.0MHz and damping ratios. From experimental investigation, similarly to SF6, it might be possible to reduce the test voltage of CO2 gas insulation system by evaluating actual lightning surge waveform in terms of the equivalent standard lightning impulse waveform.