Analysis of Accelerated Multi-Factor Aging Tests on the Winding Insulation System of Generator Stator Bars Used in Large Rotating Machines

This work examines the effect of thermal, electrical and mechanical stress on the electrical insulation system of generator bars. For this purpose, test bars are aging simultaneously and subjected to stress until the insulation fails. The acceleration is achieved by increasing the mechanical stress. In order to detect possible damage, dissipation factor as well as partial discharge measurements are performed. Furthermore modal analysis is used to identify the appearance of defects. The results are set in context to previous studies to analyze multifactor aging mechanisms in highly stressed electrical insulation systems used in rotating machines. This enables further investigation on the aging process regarding lifetime estimation.