Hybrid Method for Measuring Rotor Bar-Lamination Contact Resistances

The paper presents a new non-invasive method to estimate the contact resistance between the aluminum bars and the rotor laminations of induction motors. The methodology is based on a mix of experimental data and FEM-based simulation results. It has been applied with success to a 4-poles 15 kW squirrel cage induction motor obtaining interesting outcomes. The quantification of the contact resistance allows accurate computation of the interbar currents as well as the related additional Joule losses, opening a new understanding of this complex phenomenon and its impact on the stray losses.