Determination of the Degradation Equation for Medium Voltage XLPE Cable at 22 kV

The degradation of insulation in electrical conductors is influenced by five main factors: humidity, temperature, mechanical stress, electrical stress, and the presence of chemical elements in the installation environment. This study focuses on analyzing temperature, which is considered the most impactful variable affecting insulation resistance and, consequently, degradation. Although mechanical stress was excluded due to its minor influence in this context, its relevance in cases of improper conductor handling is acknowledged.Based on the results obtained in this study, a degradation equation for the insulation of XLPE (cross-linked polyethylene) medium voltage (22 kV) cables has been determined. The conductor was subjected to accelerated aging for 507 days using the overload technique. Throughout this period, data were collected monthly using tools such as a megger, an ammeter clamp, a thermal imaging camera, and a hygrometer. The results indicate that insulation resistance decreases with increasing temperature, while higher short-circuit currents accelerate thermal aging.The analysis includes the calculation of the polarization index (PI), allowing for the categorization of insulation condition and future projection of its evolution. Using the Arrhenius equation, which is commonly applied to estimate chemical material degradation, a model was developed that correlates temperature, current, voltage, and conductor properties to estimate insulation lifespan. The data suggest that under normal operating conditions, the insulation has an estimated lifespan of 6.75 years, validating the proposed model.This study introduces a predictive tool to determine the degradation rate of XLPE cables under various operational conditions, contributing to the development of more reliable and secure electrical networks.