Accelerated degradation of shipboard high-voltage insulation under combined electrical and thermal stress

High-voltage insulation materials used in marine environments are subjected to simultaneous electrical and thermal stresses, which critically affect their reliability. However, previous studies have primarily investigated these factors independently. This study experimentally evaluates insulation degradation under combined stress conditions in accordance with IEC 60,034-18–33 standards.F-class (155 °C) insulation materials, widely applied in marine high-voltage systems, were tested under electrical stress alone (12.54 kV) and under combined electrical and thermal stress (12.54 kV, 155 °C). The results indicate that breakdown time was reduced by 83.25% under combined stress, demonstrating a significant acceleration of degradation.Experiments were conducted using a dry oven equipped with high-voltage bushings, and breakdown times were analyzed through failure time assessment and statistical validation. The analysis identified partial discharge, electric field concentration, and chemical decomposition as the principal degradation mechanisms.This study provides empirical evidence of the synergistic effects of electrical and thermal stress and offers valuable insights for optimizing insulation material selection, advancing diagnostic techniques, and establishing predictive maintenance strategies to enhance the reliability of high-voltage systems in extreme marine environments.