Abstract
We observed current pulse waveforms of partial discharge (PD) in SF6 gas to investigate the PD mechanism. We also measured light intensity and light emission image of PD simultaneously under different condition of applied voltages and SF6 gas pressure. From these experiments, we found that the “double peaks current waveform” appeared at high pressure and high voltage condition. We also analyzed the mutual correlation of waveforms between a single current and the light emission.
Moreover, we obtained the experimental evidence of filament like light image appeared at PD tip under the same condition with double peaks current waveform. From the electric field analysis around the needle electrode tip, we believe that the filament like light image expands beyond the critical electric field of SF6 gas. Thus, we concluded that these current waveforms with double peaks showed the evidence of leader type PD, leading to breakdown. Finally, we could point out that the leader type PD should be distinguished and measured for the diagnosis of GIS insulation performance.
