Towards a holistic approach to inverter-fed machine design: FEM-based PDIV prediction of complete windings

The Schumann inception criterion was used to predict the partial discharge inception voltage of insulation models representing both wire wound and form wound (hairpin) low voltage machines. It was found that the fitting parameter K (the logarithm of the critical number of electrons that define the transition from Townsend to streamer discharge) is almost independent of material parameters when dealing with a given type of insulation (e.g., turn-to-turn using round conductors or flat conductors). These numbers can be fed to software for finite element analysis to provide a worst-case estimate of the partial discharge inception voltage.