Statistical approach for predicting remaining life of crosslinked polyethylene insulated cables

Abstract

This study focuses on developing new remaining life model of the Cross linked polyethylene (XLPE) insulated medium voltage cables that are in use for hot and dry climate. Cross linked polyethylene insulating material degrades under the service condition acted upon by thermal and electrical stresses. Degradation of the materials is quantified by two main parameters Fourier Transform Infrared (FTIR) value and strength to withstand the electrical breakdown voltage. These parametric changes obtained by accelerated aging procedure developed with the help of Arrhenius Equation are tested for significance with that found in field aged cable with the help of statistical tools. Anderson-darling test for normality, Analysis of Variance (ANOVA), and one and two sample t-test were used to validate the lab aging procedure with field aging. New aging model, based on two parameters, Fourier Transform Infra Red (FTIR) spectrum value and Electric Breakdown voltage (EBV), was developed to quantify the current equivalent age of the cable and hence remaining life of the cable. The model is validated for different field aged cables in this study.