Impact of the aeronautic environment on the Partial Discharges Ignition: A basic study

The ever increasing demand of electric power for the new aircrafts generation in the frame of MEA "More Electrical Aircraft" or AEA "All Electrical Aircraft" will result in an increase of the voltage level. This increase may induce the ignition of "corona" or ore generally speaking "Partial Discharges". These later, known as the silent enemies, will affect the reliability of the system. However when dealing with Partial discharges, not only the voltage magnitude has to be taken into account but also the environment surrounding the Electrical Insulation Systems (EIS). According to the nature of the electrical equipment, its location may be in pressurized or unpressurized areas. Thus, the environmental conditions may change from -60degC to +180 degC from Atmospheric pressure to less than 125 mbars and for relative humidity ranging between nearly zero to 100%. Since all these parameters may affect the Discharge Inception Voltage (DIV) of the equipment, it is necessary to evaluate their impact and the classical Paschen Curve has to be re plotted according to these parameters. Therefore, an experimental set-up allowing the determination of DIV between two spherical electrodes placed into a cell where the environmental conditions (pressure, R.H, T) may be controlled has been built. In this paper we will present this set-up. We will then give and discuss the main results we have obtained. The main goal of this work is to determine the worst environmental conditions leading to PD appearance and to reinforce EIS in order to endure them or to avoid their appearance thus increasing the reliability while in operations. All these points will be detailed in the full paper.