Interaction Mechanism between Conductor and Ground Insulation of Stator Windings

In order to get fundamental knowledge in clarifying thermal stress induced in stator windings, the interaction mechanism between the conductor and ground insulation of stator windings under axial load were examined theoretically and experimentally. The stress analysis was carried out with the aid of an equivalent model in which the stator windings were regarded as a composite structure consisting of the conductor and ground insulation bonded to each other by the adhesive. A series of tests were carried out on six different kinds of test bars. The strain distribution on the insulation surface was measured by strain gauges under axial load. The electrical characteristics such as tan and breakdown voltage characteristics were also measured under axial load. The relationship between variations in the electrical characteristics and the occurrence of mechanical damages is discussed. The failure mechanism of the stator windings under axial load is also revealed.