Electrical aging tests on different nanostructured enamels subjected to severe voltage waveforms

Nowadays electrical motors used in industry applications are usually coupled with inverter drives so that the stator motor windings are subjected to severe voltage waveforms such as PWM. When electrical motors having stator windings realized by means of type I random wire wound are subjected to these kinds of voltage waveforms, reliability problems due to degradation phenomena increase. In this research work different insulating nanocomposite enamels have been analyzed: suitable twisted pair specimens insulated by the studied enamels have been prepared and tested. Breakdown voltage tests and electrical aging tests have been performed: during the electrical aging tests the specimens have been subjected to pulsed voltage waveforms having amplitude higher than the partial discharges inception voltage level in order to operate in presence of partial discharges. Enamel breakdown condition has been chosen as end-point criterion and both the relevant voltage breakdown and life time values have been collected and compared. Analyzing the obtained results it has been possible to point out the behavior of the different insulating organic enamels when subjected to electrical degradation phenomena.