Study of Partial Discharge Behavior at Flight-Altitude Pressures under 60 Hz and Impulse Voltages for Samples Related to Aircraft Motors

More electric airplane (MEA) calls for higher aircraft electric system voltage level and more implementations of inverter-controlled machines, which make partial discharge (PD) a more urgent issue. Although several PD standards exist for power frequency voltage (up to 400 Hz) under normal pressure conditions, there is a lack of a well-established test procedure and standard for PD induced by ac and impulse voltage under low pressure conditions. Thus, in this paper, experimental results and associated analysis for samples of aircraft motor-related components under various pressures with 60 Hz and impulse voltage excitations are presented. The samples involved are twisted pairs, shielded wires, printed circuit boards (PCB) and a motorette. Test pressures involved the range from 87 Torr (50,000 ft.) to 760 Torr (sea level). Observations, statements and hypotheses on low pressure PD behavior under both 60 Hz and impulse excitations are put forward, based on test results.