Surface PD evolution of conventional and nanocomposite enamels

The stator motor windings of low voltage rotating electrical machines are usually insulated by organic enamel. When the motors are supplied by power electronic converters, the stator insulation system is subjected to pulsed voltage waveform and a fast degradation of the insulating system could occur. In fact, it is possible that partial discharge (PD) activity incepts leading to the deterioration of the insulating system. In this work the evolution of partial discharges is monitored when twisted pairs of copper enameled wires are subjected to sinusoidal and pulsed PWM-like voltage waveform. Conventional and nanocomposite enamels have been considered monitoring the behavior during the degradation processes evidencing the main peculiarities of each enamel when subjected to the PD action.