･Outline
The overvoltage waveforms occurring in the actual field are different from the standard lightning impulse waveform (1.2/50 μs) used in the test. We developed a method which converts a non-standard waveform into a standard-waveform for the purpose of the insulation specification.
・By applying the method, the insulation specification of gas insulated switchgears (Lightning Impulse Withstand Voltage) can be reduced by 10%-30%, and consequently the costs reduced by 5%-10%.
・This method was adopted in TEPCO and achieved cost reductions; it is also adopted by CIGRE (International Council on Large Electric Systems) . Furthermore, this study is going to be approved as an insulation evaluation method in the IEC (60071-2).