Analysis of standard parts aging under partial discharges for airborne applications

The purpose of this work is to study the behavior of airborne standard cables and connectors, when they are submitted to partial discharges. Experimental investigations are carried out: standard parts are placed at low pressure (100 mbars) and a squared bipolar high voltage of around 10kHz is applied, between 110% and 120% above the Partial Discharges Inception Voltage (PDIV). The partial discharges provoke an erosion of the insulation, and an electrical aging of the components. Breakdown is observed after a few hundreds of hours, depending on tested vectors. The PDIV is regularly recorded during the aging testing. Two different behaviors are observed: for the tested cable bundles, the PDIV decreases during the aging test, while for the tested connectors, surprisingly the PDIV increases during the test. In order to explain these phenomena, a numerical tool is used, by coupling an electrostatic solver to Paschen law and predict triggering of Townsend discharges. In the case of cables, a good correlation is obtained, with less than 20% of deviation between numerical and experimental results. In the case of connectors, the correlation is not straightforward and further investigations are in progress. In any case, these standard parts should not be used above the PDIV, and partial discharge free components need to be developed.