Insulation Aging a Historical and Critical Review

The role of insulation functions is reviewed. In this light, a history of thermal evaluation is outlined with special emphasis given to the milestones set by Steinmetz, Lamme, Montsinger and Dakin. The philosophy of functional evaluation and temperature classification isdiscussed.The aging phenomenon, applicable to various systems, is analyzed witha point of view of identifying those knowledge gaps that bar the developmentof specific aging technologies. Emphasis is given, in thisdiscussion, to the aging problems in multi-stress and/or multi-environmentalconditions. The need for a better acquaintance with material responseis stressed to develop multi-factor testing, identify materialcompatibilities, and develop nondestructive aging techniques.