High frequency and high voltage tests on electric motors stator windings

The influence of a PWM waveform on motor insulation lifetime is studied. In the first stage of the work, tests are performed on a motor, reproducing its working conditions: by means of suitable taps, the turn-to-ground voltage existing on the turns of the first two coils as better specified below are acquired. Afterwards ageing tests are performed on parts of stator windings applying test voltages whose parameters have been chosen on the basis of the previously described measurements.