The effect of charge mobility on partial discharge characteristics of enamelled wires for PWM-controlled motors

Partial discharges, which may occur in motor windings supplied by power converters, are associated with space charge accumulation. Space charge is able to modify the electric field which sustains partial discharges, affecting amplitude, repetition rate and inception voltage. This paper presents a simplified model which takes into account the dynamic of charge accumulation generated by the partial discharge process. In particular, among electrical properties surface conductivity is considered and related to the electric field governing partial discharge activity.