The Risk of Insulation Thermal Runaway in Electrical Machines Used in Traction Electrification

In this study, electro-thermal aging was conducted on an insulation system model to assess its suitability for electric transportation. A full-size stator model was exposed to thermal stress at 150°C, to simulate machine hotspot, while electrical stress was applied using a square voltage waveform resembling real service conditions. An unexpected increase in dielectric losses within the insulation model, primarily attributed to dipolar polarization in the potting resin, resulted in excessive internal temperatures of the insulation system, exceeding 200°C. These findings emphasize the importance of accounting for dielectric losses in converter-fed machine design to prevent insulation degradation and potential material incompatibilities.