Insulation characteristics of GIS for non-standard lightning surge waveforms. II. Gas gaps and spacer surface

Evaluation of lightning surge waveforms which actually enter into gas-insulated substations (GIS) is important when investigating the test voltage of equipment. The waveform of the standard lightning impulse waveform (1.2/50 μs) is used for testing; however, the lightning surge waveforms in actual fields are complex waveforms in which various different oscillations are superimposed. Investigation of the insulation characteristics of the equipment against the complex waveforms and against the standard waveform has significant importance. The insulation characteristics of GIS were investigated for these waveforms. In this part of the paper, three types of typical nonstandard waves were selected as a result of investigation of the actual lightning surge waveforms. V-t characteristics of the gaps and the spacer surface in the SF₆ gas atmosphere were compared for the nonstandard waveform and for the standard waveform