High-voltage and partial discharge testing techniques for space power systems

Simulation of Space Charge Impact on Partial Discharge Inception Voltage in Power Busbars Dedicated to Future Hybrid Aircrafts

“…Electric field massively increase in air despite small implanted heterocharge densities. Resulting electric field in air is seven times higher than breakdown threshold necessary to initiate partial discharge [11]. Simulated electric field reaches up to 22 kV/mm for only 2 C/m 3 of heterocharges density.…”

“…Added to materials defects (structural and chemical defects, electronic traps distributions, trapping level…), these partial discharge inceptions locally increase the electric field within the dielectric material. This local increase in electric field changes the intrinsic material properties and reliability, with the consequence of an irreversible insulators damage of dielectric that can affect the insulation system and then expose the power converters on which the propul-sion depends on [11]. Simulation proposed in this study aims to prevent the partial discharges risks in such systems.…”

“…((a), (b)) classic busbars configuration, ((c), (d)) curving busbars configuration. Non-charged dielectrics (PTFE).From a partial discharges point of view, for a DC 2.5 kV/mm applied voltage, both configurations lead to a much higher electric field than the breakdown field admitted in air at atmospheric pressure and at ambient temperature (  3 kV/mm)[11] [12]. Implying that air is, among the three materials, the most exposed to partial discharge risks, because of its low permittivity, ionization processes more accentuated in air and avalanche mechanisms speed occurring inside which facilitate others electronic processes.…”

Defining safe operating voltages for aerospace electrical systems

“…It is well known that discharges occur more readily (Le. at lower voltages) at lower pressures and higher temperatures as long as the Paschen's minimum has not been crossed [2,3,4]. Aircraft systems clearly operate at lower pressures and higher temperatures than ground based systems, the pressure at 40,000 feet being around one-tenth of atmospheric and the electrical systems within the aircraft engine being exposed to temperatures of some 220°C.…”

Dielectric breakdown of polypropylene under high frequency fields

“…In particular, there is a steep reduction in the dielectric strength when the frequency is increased from 5kHz to 3OkHz. It is well known that partial discharge activity in the microcavities is accelerated with an increase in frequency [9]. This combined with an increased heat loss at the high frequency most probably leads to the reduction in the breakdown voltage.…”