Thermal Accelerated Aging Methods for Magnet Wire: A Review

This paper focuses on accelerated aging methods for magnet wire. Reliability of electrical devices such as coils, motors, relays, solenoids and transformers is heavily dependent on the Electrical Insulation System (EIS). Accelerated aging methods are used to rapidly simulate the conditions in real life, which is typically years (20,000 hours) depending on the operating conditions. The purpose of accelerated aging is to bring lifetime of an EIS to hours, days or weeks. Shortening the lifetime of an EIS to such an extent, allows for the study of the insulation materials behavior as well as investigate ways to estimate the remaining useful life (RUL) for the purpose of predictive maintenance. Unexpected failures in operation processes, where redundancy is not present, can lead to high economical losses, machine downtime and often health and safety risks. Conditions, under which thermal aging methods are generally reported in the literature, typically neglect other factors, owing to the sheer complexity and interdependence of the multifaceted aging phenomena. This paper examines some existing thermal aging tests, which are currently used to obtain data for enamel degradation in order to try to better understand of how the thermal stresses degrade the EIS. Separation of these stresses, which the EIS operate under, can yield a better understanding of how each of the Thermal, the Electrical, the Ambient and the Mechanical (TEAM) stresses behave.