MODELS FOR INSULATION AGING UNDER ELECTRICAL AND THERMAL MULTISTRESS

A review of the methods and models used in lifetime studies of solid insulators under single and multiple stress conditions is presented. The statistical methods used with this type of data are briefly described. These statistical methods include the two-parameter Weibull distribution and the log-normal distribution which are the two distributions most frequently used in aging studies. Most attention is given to lifetime models under multiple stresses which have recently generated considerable interest. In particular, several models under combined electrical and thermal stresses are presented and their applicability is analyzed and discussed. These include the multistress models proposed by Simoni and Ramu, both employing the inverse power law for electrical aging, the exponential model by Fallou, the probabilistic model by Montanari, and the physical model by Crine. This paper discusses trends in the development of these models. © 1990 IEEE.