The work presented here is part of a larger study concerning the analysis of electrical stress and degradation phenomena of electrical insulation of low voltage machines fed by Pulse Width Modulation (PWM) controlled inverter. The goal is to assess the risk of partial discharge (PD) in stator windings of rotating machines. In this objective, two complementary approaches are adopted: electrostatic simulations using Finite Element Method (FEM) in 2D approximation, and experimental measurements. The model seems to be a good tool allowing an approximation of PD occurrence in a given wire type. In the experimental part of this study, a simple and efficient method to detecting PD under PWM controlled voltage is presented.