Non-intrusive partial discharges investigations on aeronautic motors

The present paper reports on a study of non-electrically intrusive partial discharge investigations on an aeronautic motor. Relevancy, robustness and repeatability of partial discharge testing procedures, both on insulating materials characterization and on operating aeronautic equipment are essential to ensure reliability of the aircraft systems. The aim of this paper is to be the very first step of defining such procedures and the associated test equipments. To do so, the paper will start by providing an understanding of partial discharge phenomena and will review typical more electrical aircrafts architectures and their key characteristics causing partial discharge risk to increase. The impact of harness length, high performance power electronics and increase of voltage level on insulation system is demonstrated. Then, an analysis is conducted from motor design point of view to find out which test procedures are relevant to each insulation system performance both at atmospheric pressure and reduced pressure. The study helps to realize the benefits of using multiple test samples and procedures to assess insulation system performance levels through the design process of the motor. It is shown that a good agreement is find out between the stator and representative samples. This paper will also review the ability of the non-intrusive test method used to detect partial discharge with a full scope of voltage signal from AC to impulse voltage and under different pressure. The paper is concluded with analysis of results and thoughts about future work regarding motor design taking into account partial discharge risk and evolution of proposed procedures.