Analysis and Experiments for Thermal Stress of Totally Impregnated Stator Windings

Recently, medium-capacity electrical rotating machines usually have been made by the total impregnation process, through which the stator windings and core are rigidly bonded together. When such machines start or are in the heat cycle, thermal stress takes place among conductor, insulation wall, and core. This paper theoretically analyzes the phenomena of thermal stress and confirms the results experimentally. A procedure to reduce stress is also presented.