Thermal Performance Evaluation of T-Shaped Cables Insulation Using Intelligent Heating and Infrared Thermography

Thermal stress is a leading cause of degradation and failure in XLPE insulated medium voltage power cables, yet reliable in-service monitoring methods remain limited. This study developed novel experimental platform combining intelligent heating and infrared thermography to characterize thermal dynamics in cable T-joints aged one and three years. Under controlled laboratory conditions with a 40° C heat source and 14° C ambient temperature, temperature responses are monitored across thin outer, thick outer, and internal layers. Results indicate markedly faster initial heating in thin versus thick layers (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.0217^{\circ} \mathrm{C} \min$</tex> vs. <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.0066^{\circ} \mathrm{C} \min$</tex>), greater stabilization delays (480 s vs. 660 s), and amplified temperature variability in aged joints (standard deviation increase of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{1 0 0 \%}$</tex>). A twolayer heat transfer model is formulated with age-dependent time constants (new: 0.025-0.03 s <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${ }^{-1}$</tex>; aged: <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.055-0.065 ~\mathrm{s}^{-1}$</tex>). Moreover, surface temperature forecasting is achieved using an LSTM predictor with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\leq 1.2 \%$</tex> error. These contributions enable in-service diagnostics and predictive maintenance for wind farm cable assets by quantifying age-dependent thermal signatures and forecasting thermal behavior.