Aging tests on type I insulating systems applying pulsed waveform

Nowadays the massive adoption of electronic converters to supply induction motors leads to critical problems during the normal operation. One of the most investigated problem is the unexpected early failure of the stator winding insulation. When the motors are supplied by electronic converters, the stator insulating system could be subjected to overvoltages due to resonance and reflection phenomena. If these overvoltages exceed the partial discharges inception voltage, partial discharge activity incepts. The erosion of the enamel used to insulate the stator winding wires, due to the presence of partial discharges, leads to the degradation of the dielectric characteristics of the insulating system and to a total breakdown conditions in the short-medium term. This test campaign aimed at the investigation of the unipolar pulses voltage waveforms role on the degradation of Type I stator winding insulation systems.