Partial discharge behavior and insulation failures detection in electrical devices subjected to impulse voltage excitation

• Calibratable partial discharge measurement method for impulse voltage excitation. • Signal processing to extract partial discharge signals despite source disturbances. • Characteristics of four different partial discharge sources at pulse voltage. • Pulse voltage amplitude-dependent magnitude, probability, and delay as PD features. • Theory of partial discharge mechanisms at pulse voltage derived from measurements. Partial discharges can occur within an insulating system due to flaws in the material and can cause continuous deterioration until a full breakdown occurs. Modern insulating systems are subjected to various forms of pulse voltage excitation, mainly due to the switching of modern power electronics. The recent introduction of wide-bandgap semiconductors increases this stress by enabling higher operating voltages and steeper switching transients than silicon-based semiconductors. Within this paper, partial discharge measurements are performed to investigate the discharge behavior of different partial discharge sources at impulse voltage excitation, aiming to find characteristic features. The presented method relies on measuring the conducted electrical signal of a partial discharge and can, therefore, access all quantities known from partial discharge measurements at sinusoidal voltage. This article introduces the high voltage measurement setup and the signal processing required. Experiments on four different partial discharge sources are performed, and the measured data are evaluated for the information they possess regarding the active discharge mechanisms. With the results obtained, the fault analysis can be extended to recognizing the fault type active at pulse voltage, utilizing partial discharge measurements.