PD current pulse waveforms of environmental friendly gases measured with SHF_PDPW system and the applicability of the UHF method

This paper deals with PD current pulse waveforms of environmental friendly gases such as N₂, CO₂, dry air, and CF₄ gas that were measured with the SHF_PDPW (Super High Frequency wideband PD current Pulse Waveform measurement) system. This specially developed system enables us to obtain accurately PD current pulse waveforms up to the SHF band (330GHz). When one discusses the UHF method for the insulation diagnosis, we believe that the most important thing is to accurately measure and deeply understand the PD current pulse waveform because it is the source generally having a very steep rise time below 1ns that gives the features of the emitted electromagnetic (EM) waveform. So far, we have investigated PD current pulse waveforms in SF₆ gas with the SHF_PDPW system and showed the very steep waveforms with a few tens pico seconds rise time and distinct difference in the wave shape between positive and negative corona. To compare these new findings, we similarly investigated the PD current pulse waveforms of the environmental friendly gases. Also, we measured PD-emitted EM waves simultaneously with the PD current ones and discussed the applicability of the UHF method to these gases.