Partial Discharge Assessment for High-Voltage Electric Machines for Aircraft Propulsion Applications

This paper presents the proceedings related to the assessment of the insulation of high voltage electric machines and the arcing effects that may occur within the system. In this work, an overview of the state of the art of partial discharges (PDs) on the insulation of electric machines for aircraft applications is developed introducing PDs and the existing work regarding their detection, with a focus on aeronautical propulsion. A classification of the PDs is presented, as a function of the topology of the discharge and the medium surrounding the test unit. Moreover, different aspects of this phenomena are assessed such as the detection methods of Phase Resolved Partial Discharge (PRPD) patterns, acceptance limits and the time-frequency map. Additionally, the state of the art regarding the ageing of different insulation materials under electric stress is examined. On the other hand, dielectric strength tests have been performed on insulating materials to assess the influence of climatic conditions on this parameter. Finally, different partial discharge inception voltage (PDIV) prediction methods are evaluated and compared.