A study of the propagation behaviour of partial discharge pulses in the high-voltage winding of hydro generators

Rotating electrical machines are one of the key assets for a reliable power supply. An unplanned outage of such components can lead to high follow-up costs. To prevent such unexpected occurrences the partial discharge (PD) diagnosis can be a reliable instrument for detecting failures in the insulation system before major damage or a breakdown occurs. However, there have been repeated instances where the measurable apparent charge on the terminals does not correlate with damages found during inspection or repair. One important reason is the fact that PD-measuring systems with high bandwidth can only accurately measure PD-sources, which are located close to the terminals.