Simultaneous measurements of PD in oil using conventional narrow band and ultra wide band detection systems

Partial Discharge (PD) measurements were carried out with conventional narrow band and ultra wide band detector circuits on a transformer oil under ac conditions, employing point-to-plane electrodes having separations from 3.0 to 8.0 mm. The rapid rise time partial discharge events in the oil were readily detected by the conventional narrow band measuring system in the form of a single integrated apparent charge pulse. This pulse represented generally the single response to a PD pulse burst involving a number of pulses in the oil. The apparent charge values of the integrated pulse were found to range from approximately 10 to 16 pC, representing the lower range of PD apparent charge values normally encountered in oil-filled electrical apparatus when conventional narrow band PD measuring circuits are employe