Résumé
The purpose of the work is to determine the impact of a low-pressure environment on a cable lifetime for a high DC voltage in an airborne application. Space charge phenomena have long-term influence and can lead to a premature failure of a device, like a cable, so it is necessary to understand the insulation ageing process in an aeronautical environment. In this paper, we are presenting the scientific approach and the implemented study, in order to answer this question. Several samples of HVDC cables were aged with a combined electrical/thermal stress with and without a low-pressure stress typical of the aeronautical environment. The main monitored observables are the space charges within the cable insulation via the Thermal Step Method (TSM), the dielectric answer of the cable via a dielectric spectroscopy, and the chemical evolution of the material with a Differential Scanning Calorimetry (DSC). In order to dis-embed the thermal effect and the combined effect of thermal and electrical constraints, some specimens received a thermal constraint alone, with no applied voltage. Testing is on-going and it is too soon to provide consolidated results. Hence the paper is focused on presenting the experimental approach which has been implemented, and the choice of ageing markers. Biais, which might have an influence on the results, are also discussed.