Choice of optimal voltage for more electric aircraft wiring systems

Increased electrical power demands are being experienced on the new generation of aircraft due to an increased reliance on electrical technology such as air conditioning, de-icing systems and electrical flight control actuation. Distribution of power at higher voltages is therefore now being seen in modern aircraft to avoid the penalties incurred due to high wire weights. Voltages have increased past the minimum of Paschen´s law resulting in a risk that life limiting partial discharge damage can occur in the insulation systems. This study uses a theoretical analysis backed by experimental results to investigate the optimal operating voltage of a wiring system. In addition it proposes a methodology for optimising the operating voltage level based on an analysis of the power carrying capability of wiring within a fixed volume system and the derivation of the wire weight as a function of voltage. The work done has shown that the optimal operating point for an aircraft power system does not imply the use of the highest voltage possible. A trade-off between wire weight and power transfer is required and furthermore the use of direct current systems can result in higher power transfers than conventional three phase/400 Hz alternating current (AC) systems.