Improvements on lifespan modeling of the insulation of low voltage machines with response surface and analysis of variance

The aim of this paper is to present some improvements of the method for modeling the lifespan of insulation materials in a partial discharge regime. The first step is based on the design of experiments which is well-known for reducing the number experiments and increasing the accuracy of the model. Accelerated aging tests are carried out to determine the lifespan of polyesteimide insulation films under different various stress conditions. A lifespan model is achieved, including an original relationship between the logarithm of the insulation lifespan and that of electrically applied stress and an exponential form of the temperature. The significance of the resulting factor effects are tested through the analysis of variance. Moreover, response surface is helpful to take into account some second order terms in the model and to improve its accuracy. Finally, the model validity is tested with additional points which have not been used for modeling.