Converter Stress Impact on Thermally Aged Resin for Low-Voltage Machines

Qualification according to IEC 60034-18-41 considers the partial discharge inception voltage (PDIV) equivalent under different test voltage waveforms, assumption that can be surveyed. PDIV tests have been performed on unaged and thermally aged impregnated twisted pairs, models of the turn-turn insulation. Results revealed that the PDIV under SiC impulse voltages seems to be larger than the one achieved using AC sinusoidal voltages, but only for new samples as after aging they drop to comparable values, implying a larger reduction for the former. In this framework the resins play an important role, increasing the PDIV and hence helping achieving the desired reliability. Therefore, the evaluation dielectric properties of the resin became crucial for ensuring its performance.