Partial discharge measurements in SF/sub 6/ and air using phase-resolved pulse-height analysis

Carries out a study on partial discharge (PD) phenomena in SF/sub 6/ gas and tries to construct a diagnostic system capable of separating noise from observed PD signals for assessing the condition of insulation performance in power apparatus. The authors have constructed a computer-aided PD measuring system which permits a time-sequential data acquisition and phase-resolved pulse height analysis. Using the PD measurement system, the authors measured 60 Hz AC PD in SF/sub 6/ gas and in air at atmospheric pressure for needle-plane electrodes with three different radii at the tip of the needle, 3, 30 and 500 /spl mu/m. They proposed particular PD statistical parameters, unbalance ratios U/sub T/ and U/sub q/ of the pulse repetition rate and average of charge, respectively, between positive and negative PD pulses occurring per cycle; these parameters proved to be good indicators to distinguish PD occurring in SF/sub 6/ from that in air. The mechanism of PD inception was also discussed.<
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