Specific Heats of a Magnet-Wire-Varnish-Enamel Combination as a Measure of Thermal Stability of the Insulation System

Changes in specific heat with time and temperature have long been used as an indicator of changes of state or of chemical changes. The differential-thermal-analysis (DTA) technique has been used to study both magnet-wire enamel and enamelvarnish systems. Polyimide enamels were studied to try to relate results to degree of cure and thermal life. The problem is complex but may ultimately lead to more meaningful relationships.