Single and coupled mechanical and thermal responses investigation of synchronous generator winding insulation consideration axial static air-gap eccentricity

Extensive research has focused on the electromagnetic and thermal properties of the syn generators, primarily examining the core and windings. However, the stator winding insulation is a critical yet often overlooked vulnerable component. This paper investigates the mechanical, the thermal, and the coupling characteristics of winding insulation under axial static air-gap eccentricity (ASAGE) condition. The theoretical models for losses and electromagnetic forces in the stator core-winding system under ASAGE are established. The temperature of the stator core-winding system and end-winding vibrations are comprehensively investigated. Through electromagnetic-thermal-structural field coupling calculations, mechanical, thermal, and coupled structural responses of the winding insulation under ASAGE are quantified and compared. It is found that that ASAGE elevates both temperature and vibration in winding insulation. At 5 mm axial eccentricity, the insulation’s maximum temperature increases by 3.86 °C, while the 2nd harmonic vibration amplitude rises by 282.35%. Meanwhile, structural responses exhibit increased magnitudes and asymmetry distribution. Coupled stress amplitude escalates by 44.58%, with end-to-end stress asymmetry reaching approximately 5.25%. Critical vulnerability positions are identified at the insulation’s nose end and the junction between its straight and involute segments. Based on these response patterns, common insulation failure positions and wear mechanisms are characterized to inform preventive strategies.