Measurement of partial discharges at rapidly changing voltages

This work presents a measuring system for PDs at repetitive voltages with short rise times, based on a coupling device adapted for this kind of voltages and a method for removing contributions from the applied voltage. The potential of the system has been demonstrated through measurements of PDs around a needle in air at voltages of 5.5 kV - 9.5 kV with rise times down to 10 mus. The observations obtained with this PD source prove that the measuring technique described enables detailed studies of PD properties under repetitive rapidly changing voltage waveforms in the investigated range of voltages and rise times.