Analysis of life time estimation methods based on data for electro-thermally aged PET films

Several empirical formulas have been proposed for lifetime prediction of electrical insulation that works in an electric field and at elevated temperatures. However, it is not obvious which of them is applicable to different types of insulating materials. An attempt is made to determine which of the models best describes experimental aging data for polyethyleneterephtalate (PET) films. Out of the analyzed empirical models for electrothermal aging of electrical insulation, the best approximation of the experimental data considered was provided by L. Simoni's model (1985). Constant lifetime characteristics elaborated on its basis are of practical importance and may be satisfactorily used in practice. Application of the model of J.P. Crine (1989) allowed the calculation of the free energy and the mean free path values for the studied PET films.<
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