Jordan Jamesona, Michael H. Azariana, and Michael G. Pecht a
a CALCE, Center for Advanced Life Cycle Engineering, Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, USA
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.