Polyimide is one of the most heat resistant polymers with high electric breakdown strength, good mechanical properties, and chemical resistance. Polyimide is used in severe environmental condition. Polyimide is commonly applied as electrical insulation in a fine gauge of invertered motor windings and in high voltage coils of encapsulated fly-back transformers. The wire insulation may be exposed to multi-stresses like ac, dc high voltages, temperatures etc. In this thesis, magnet wire insulation properties under multiple stresses are studied under ac, dc voltages and high temperatures. Accelerated degradation test is used to do study of Life -time characteristics of Magnetic wire MW 16-C, which has polyimide insulation. The results of accelerated aging test are evaluated with statistical tools Weibull and ALTA. The result shows that the time to failure can be represented by the inverse power law and the Arrhenius equation with respect to test voltage and temperature respectively.

Electrical and electronic device insulation systems experience multiple stresses while in service. Insulation design engineers usually make attempts to study the behavior of insulation under multiple stresses to keep the size and weight of the electrical insulation at a minimum. In this thesis, magnet wire insulation properties under multiple stresses are studied. Magnet wires are used for insulation in transformers, flyback transformers, solenoids, sensors, motors, adjustable speed drives etc. The magnet wire insulation under study in this work is micrometers thick, yet they are expected to provide high breakdown strength, good windability, and resistance to moisture. Accelerated life tests are performed on two different AWG 43 magnet wires. Combined Weibull Electrical-Thermal life models and Electrical-Thermal-Frequency life models were successfully verified in this work. The statistical information like lifetime characteristics, probability of failures, and lifetime percentiles determined for the two different magnet wire insulation is helpful for a better understanding of their insulation properties.