High bandwidth measurement of partial discharge current pulses

This paper presents the first measurements of partial discharge current pulses captured using both a high analogue bandwidth and an extremely fast sampling rate. These pulses are of interest because when they occur in gas insulated substations they generate UHF signals that can be used to detect internal defects. A special test cell was designed to enable direct measurement of particle generated pulses under conditions similar to those present in high voltage gas insulated apparatus. The analogue bandwidth of the measurement system is in excess of 4.0 GHz and the single-shot sampling rate is 102.4×10⁹ samples s^-1. A signal processing scheme used to compensate the measured pulses is described. Results presented show individual current pulses from moving particles in SF₆. The measurements demonstrate that the pulse widths and risetimes are shorter than has previously been established