Lifespan and aging modeling methods for insulation systems in electrical machines: A survey

This paper deals primarily with modeling lifespan and, to a lesser degree, aging in insulation systems of electrical machines. The different aging processes involved, including partial discharges, are described. Previous works, in conjunction with the current study, are described and lead to the conclusion that there is no single method, even with accelerated lifetime tests, able to provide lifetime models taking into account all the stress factors in a simple way. Consequently, the principles of different regression methods are described (design of experiments, response surface, multilinear and robust regression) and applied with a limited number of experiments, thus reducing experimental cost. Several types of insulation material were tested in order to confidently recommend one in particular.