Characteristics of Partial Discharges on a Dielectric Surface in SF6-N2 Mixtures
X. Han, Yicheng Wang, Loucas G. Christophorou, Richard J. Van Brunt
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 shown1-3 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.
, Wang, Y.
, Christophorou, L.
and Van Brunt, R.
Characteristics of Partial Discharges on a Dielectric Surface in SF<sub>6</sub>-N<sub>2</sub> Mixtures, Proc., Intl. Symp. on Gaseous Dielectrics, Virginia Beach, VA, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=5578
(Accessed December 6, 2023)