Discharge pattern recognition in high voltage equipment

For a long time recognition was performed by eye, studying PD patterns at the ellipse at an oscilloscope screen. In recent years the use of computer-aided processing provides automation of the recognition procedure. As a result, the partial discharge (PD) pulses are grouped by their phase-angle with respect to the sine wave. Consequently, the voltage cycle is divided into phase windows representing the phase angle axis 0-360°. If the observation takes place for several voltage cycles, two- or three dimensional patterns can be observed