Comprehensive Investigation of Thermal and Mechanical Loads on Stator Winding Insulation in Nonsalient Synchronous Generator Under RISC Fault

Current studies on frequent rotor interturn short circuits (RISCs) primarily focus on fault diagnosis. However, the detrimental effect of RISC on the fragile stator winding insulation of synchronous generators is overlooked. Consequently, this article comprehensively investigates thermal and mechanical loads, as well as the structural responses of the stator winding insulation. The impact of RISC fault on the thermal and mechanical degradation distribution patterns of the insulation is explored in detail. Besides, different from the current research on RISC, this study considers a broader range of influencing factors, including degree, position, contact resistance, and output. In this article, detailed theoretical models for calculating thermal and mechanical loads are presented. Finite element analysis (FEA) and experiments are conducted on a 5-kW synchronous generator to calculate and test thermal and mechanical loads on the insulation. The mechanical, thermal, and coupling structural responses of the insulation are obtained and compared. The results indicate that maximum insulation structural responses caused by mechanical loads, thermal loads, and coupling actions are most pronounced at the nose end and the junction between the straight and involute lines, warranting careful attention. This study offers a unified approach and a practical framework for extended insulation service life.