PDIV Modelling for Rectangular Wire Turn-to-Turn Insulation of Inverter-Fed Motors through Thermal Ageing

This contribution develops the partial discharge inception voltage (PDIV)-FEM-based model based on Schumann’s streamer inception criterion (SCSIC) with respect to thermal ageing time (TAGT) or the insulation lifetime for the turn-to-turn insulation of coil winding made by rectangular insulated wires. The accelerated thermal ageing is performed at 250°C, which is 50°C higher than the thermal class, with ageing intervals of 156 and 312 hours. PDIV measurements are conducted at a constant temperature of 25°C, 40% relative humidity, and atmospheric pressure (1013 mbar). The measurements are done under AC 50 Hz excitations, following IEC 60034-18-41 guidelines for inverter-fed motor insulation system qualification. Furthermore, this study analyzes streamer inception parameters such as critical field line length (CFLL), effective ionization coefficient (α eff ), partial discharge (PD) inception field ( E discharge ), firing voltage (V firing ) and its correlation with PD charge amplitude as a function of TAGT or the insulation lifetime