Electrical Treeing at High Altitude: Effect of Pressure and Temperature

Aircraft electrification poses new challenges to the safe design of the insulation system under harsh operating conditions. This study focuses on the investigation of electrical treeing, a precursor to electrical breakdown in the bulk of electric wires and cables, under emulated low pressure and high temperature for high density electrification at high altitude. It was found in a model insulation of cross-linked polyethylene (XLPE) that low pressure and high temperature significantly decreased the treeing initiation voltage and increased tree growth propagation rate. Moreover, the presence and size of artificial air gaps affected tree morphology, growth rate, and fractal dimension in a way that decreases insulation durability. The effect of pressure on treeing growth was studied by using the partial discharge (PD) measurements, which suggested lower pressure increased PD activities, with respect to the rate and magnitude of PDs during both stages of treeing initiation and propagation. This work could be used as a baseline for studying electrical treeing phenomenon at high altitudes with coupled high temperature-low pressure, to pave the way for the reliable design of insulation systems on the path towards aircraft electrification.