Characteristics of Partial Discharges on a Dielectric Surface in SF6-N2 Mixtures

Published

December 1, 1998

Author(s)

X. Han, Yicheng Wang, Loucas G. Christophorou, Richard J. Van Brunt

Abstract

An important tool for improving the reliability of HV-insulation systems relies on partial discharge (PD) measurements. The assessment of the insulation failure of HV equipment using PD measurements requires an interpretation of the PD measurements themselves. The statistical characterization of pulsating PD signals has been shown^1-3 to play an important role in understanding PD phenomena. The development of diagnostic systems which utilize statistical data on partial discharges for pattern recognition is important for the identification of types of defects in electrical insulation. This paper presents the results of a recent investigation of pulsating PD phenomena occurring in point-dielectric gaps under an alternating voltage in SF₆-N₂ mixtures. The dielectric is a cast epoxy resin with Al₂O₃ filler. A computer-based PD recording system has been utilized which captures the amplitudes and time of occurrences of all pulsating PD events above a certain amplitude within an arbitrary time period. The data have been collected over sufficiently long time periods to make the stochastic analysis possible. From the analysis of the stochastic behavior, the differences of the time-resolved histograms of PD in SF₆-N₂ mixtures and air have been obtained. Due to the strong electronegative character of SF₆ and its tendency to decompose during a discharge, the PD patterns in SF₆-N₂ mixtures are notably different from those in air. The measured PD pulse rate and average current show that partial discharges in SF₆-N₂ mixtures in the presence of an epoxy surface are non-stationary, that is they very with time. Measurements made over a twenty-four-hour period show that there are different stages of the partial discharge behavior. These results are presented and briefly discussed.

Proceedings Title

Proc., Intl. Symp. on Gaseous Dielectrics

Conference Dates

June 2-5, 1998

Conference Location

Virginia Beach, VA

Pub Type

Conferences

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Keywords

dielectric surface, partial discharge, SF₆-N₂ mixture, statistical analysis

Citation

Han, X. , Wang, Y. , Christophorou, L. and Van Brunt, R. (1998), Characteristics of Partial Discharges on a Dielectric Surface in SF₆-N₂ Mixtures, Proc., Intl. Symp. on Gaseous Dielectrics, Virginia Beach, VA, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=5578 (Accessed April 26, 2024)