Performance Enhancement of MVDC Aircraft Cables Using Micro-Multilayer Insulation Under Low-Pressure Conditions

Abstract

The development of medium-voltage direct current (MVDC) cable systems for wide-body all-electric aircraft (AEA) requires insulation technologies capable of operating reliably under reduced-pressure environments. Conventional underground cable insulation, designed for atmospheric conditions, exhibits degraded partial discharge (PD) and dielectric performance at low pressure, limiting its applicability to aerospace systems. This work presents a controlled experimental comparison between a conventional single-layer extruded insulation system and a micro-multilayer multifunctional electrical insulation (MMEI) architecture, in which all cable components are kept identical except for the insulation. The MMEI system is implemented with only 10% of the baseline insulation thickness to evaluate the effectiveness of insulation architecture in enhancing performance. PD characteristics and dielectric strength are experimentally evaluated under DC voltage at atmospheric pressure and 18.8 kPa. Results show that the MMEI-based cable exhibits higher PD inception voltage (PDIV) and maintains a detectable PD extinction voltage (PDEV) under reduced pressure, unlike the conventional cable. Furthermore, despite its significantly reduced thickness, the MMEI system demonstrates a substantial increase in dielectric breakdown strength, withstanding voltages exceeding 20 kV compared to below 5 kV for the conventional design under low-pressure conditions. These findings demonstrate that insulation architecture, rather than thickness alone, governs performance in MVDC aerospace cables. The results highlight the potential of MMEI systems to enable lighter, more compact, and higher-performance cable designs for future electrified aviation platforms.