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Electrical insulation is the limiting factor that reduces the lifetime of power components. The aging of insulation, which is heavily caused by partial discharges (PDs) and harsh environmental conditions, eventually leads to complete insulation breakdown. The advancement in developing more- and all-electric aircraft is limited by the existing apparatuses that operate at lower voltages. High applied voltage and lower ambient pressure, commonly envisaged in more and all-electric aircraft, pose significant challenges, as their effects on PD activity and space charge accumulation differ, thereby affecting the apparatus's lifetime. To improve the reliability of aircraft electric motors' performance, it is essential to accurately predict the breakdown performance of the magnet wires used as windings in the motors at low-pressure levels. In this article, we investigate the effect of low pressures on the breakdown voltage of magnet wires with insulation Type I. 

This study examines how fast rise times, which are common in modern power electronics and drive systems, affect the aging of electric machine windings. It focuses on how to ensure these windings can last longer and work reliably in electrical systems. A twisted pair magnet wire with insulation commonly used in wound machines was used to get experimental data to understand how different voltage waveforms can influence endurance testing of motor insulation systems powered by inverters. Unlike past studies that looked at comparatively slower rise times and fewer repetitions, this research specifically addresses the challenges posed by next-generation wide bandgap (WBG)-based conversion systems. These systems operate at very high speeds, up to 100 kV/μs, and switch frequencies up to 500 kHz, where both frequency and rise time are crucial factors affecting insulation aging over time. 

Emerging power electronic drives and converters are planned to operate at high voltages with high switching frequencies (up to a few hundred kHz), which will affect the reliability of insulation systems of windings of electrical machines. To evaluate the insulation quality under such high-frequency pulses, lifetime test is a prominent way. For simplification of test procedure, turn-to-turn insulation samples are approved by IEC 60034-18-42. In past studies, the impact of switching frequencies has been investigated under lower frequencies (up to 20 kHz), which cannot address the challenges of next-generation wide bandgap (WBG)-based power converters. In this study, the lifetimes of turn-to-turn insulations under high switching frequencies (50 kHz) are tested at four different rise times (50 ns, 100 ns, 150 ns, 200 ns), and the impact of switching frequency on the lifetime of the insulation is analyzed.