Delamination and cracking failures in high-voltage stator winding coatings

A coupled finite element analysis is employed to understand the role that induced high voltages play in leading to stress which can initiate cracking in stator winding coatings. Specifically, the current flow due to the induced voltages is treated as a heat generating source in the wire and its coatings. This source leads to a temperature distribution in the wire which in turn develops varying states of stress in the different materials in the wire. The stress levels are then employed in a specialized finite element program designed to calculate crack propagation in plane stress and axisymmetric structures, called FRANC2D/L. Propagating edge cracks are examined at a number of sites in the coatings of the high-voltage stator winding end turn