Abstract:

The failure of insulation in electromagnetic coils is a significant cause of coil failure and can have severe implications for the system in which the coil is used. Impedance monitoring of coils has emerged as a promising avenue for evaluating the insulation health of electromagnetic coils in-situ. Due to its excellent mechanical properties and ability to endure high temperatures, polyimide is widely used as an insulator in the electromagnetic coil manufacturing industry. However, little information is known about the electrical behavior of polyimide insulation when subjected to the variety of stresses experienced when used as electromagnetic coil insulation, casting uncertainty on the use of impedance monitoring when monitoring polyimide insulation health. This paper presents an experimental analysis of how the insulation electrical parameters evolve over time, and their consequent effect on the coil impedance spectrum, thus providing useful empirical evidence for impedance monitoring for electromagnetic coil insulation health monitoring.