PD characteristics at square shaped voltages applying two different detecting techniques

Nowadays power electronic converters are widely used and the fast switching voltage fronts results in an increased stress on the insulation material and may cause a reduction of the HV systems reliability. Nonsinusoidal voltage waveform have influence on the partial discharges (PD) characteristics in insulating systems due to the increased harmonic content which causes problems mainly in electrical PD measurement setups. In fact, impulse voltages cause strong switching disturbances, which make it much more difficult to distinguish PD signals from noise. This work investigates the influence of repetitive steep pulses on different types of test objects exposed to square wave voltages applying two measurement systems each based on different detection principles, the first one based on a resonant PD decoupler and the second one on an antenna sensor with a flat frequency response and the challenges involved. Results reveal an influence of the rise time was observed with both systems however different information were available dependent on the principle used and the PD characteristic versus noise and remnants of the applied voltage.