Influence of different square voltage waveforms on the partial discharges behaviour during tests on twisted pair specimens

The present work is part of a research program aimed at studying the long-term performance of electric motor insulation systems which are part of modern drives (equipped with fast inverters/converters). In particular the degradation effects of partial discharges (PD) were here experimentally studied. Different (purposely selected and generated) PWM-like waveform voltages have been applied to twisted pairs (polyimide-imide enamelled wires) specimens. The tests have been carried out at 100/spl deg/C. The relevant PD output (patterns) has been recorded by means of a digital system and the times-to-breakdown of the specimens have been recorded. The various PD patterns appeared consistent with the recorded lifetimes and the planned study has produced both an innovative line of approach and interesting results.