Thermal Stability of Magnet Wire Evaluated by Viscoelastic Behavior

This paper outlines a method for testing the thermal stability of magnet wire by measuring the viscoelastic behavior of tubed fims obtained from magnet wire manufactured with standard equipment. It was found that there was a correlation between the glass transition temperature obtained from the mechanical tan δ versus temperature curve and the thermal class obtained from the IEEE No. 57 test method. When a magnet wire is heat aged, the mechanical tan δ peak of the film decreases. Regression curves of the mechanical tan δ peak versus aging temperature and aging time were expressed as second-order curves. The activation energies of heat aging were obtained, and compared to the activation energies obtained from the IEEE No. 57 test method.