Accelerated Life Testing of Marine Electrical Insulation Systems Based on Frequency-Dependent Breakdown Analysis

Marine power systems, including generators and transformers, experience voltage stress at various frequencies. Once the stress exceeds the bearing capacity of the electrical system, it results in insulation breakdown or failure. Therefore, extensive testing is required to ensure that marine electrical insulation systems are reliable. In accordance with International Electrotechnical Commission (IEC) standards, conventional tests at commercial frequencies require over 5000 h, making them time-consuming, inefficient, and practically infeasible. This study explores frequency-based accelerated life testing to reduce the duration of testing. Insulation systems made of mica-based corona-resistant materials and epoxy resin were tested at 60, 300, 600, and 900 Hz using a variable-frequency high-voltage tester. The results show that the time to failure decreases as the frequency increases (from 381.83 h at 60 Hz to 22.33 h at 900 Hz, a 94% reduction). Power and exponential decay models effectively describe this relationship. The power model provides a better overall fit, and the exponential decay model improves the accuracy at higher frequencies. This study confirms that higher frequencies accelerate insulation degradation, shortening test times considerably. Frequency-based accelerated testing can enhance insulation system evaluation and optimize international testing standards.