Comparative Analysis of Partial Discharge and Dielectric Strength of Multilayer Multifunctional Electrical Insulation (MMEI) Samples Under AC and DC Conditions at Atmospheric and Low Pressure

High-power density medium voltage direct current (MVdc) cables designed for electric aircraft applications must ensure reliable performance under extreme environmental conditions. To ensure safe and efficient operation, these cables need to exhibit strong resistance to partial discharge (PD) and arcing, which are critical factors affecting insulation integrity. Among the various multilayer multifunctional electrical insulation (MMEI) structures developed, the ARC-SC-T-MMEI described in this article has been selected for further investigation due to its multifunctional properties. We examine the PD behavior of the fabricated flat samples under atmospheric and low-pressure conditions to evaluate the impact of environmental variations on electrical performance. A comparative analysis of the PD characteristics is conducted using the Pearson correlation coefficient, which provides insights into how pressure influences discharge activity. The dielectric strength of the samples is assessed under both ac and dc voltage to evaluate their withstand capability and breakdown characteristics. A two-parameter Weibull distribution was employed for statistical comparison. In addition, we fabricate a cable prototype using the optimized MMEI system, analyzing its PD behavior and dielectric strength under ac and dc conditions at both atmospheric and low-pressure settings. These findings highlight the effectiveness of MMEI insulation in mitigating PD and enhancing dielectric strength, thereby advancing MVdc cable technology for electric aircraft applications.