The challenges of reliable dielectrics in modern aerospace applications: the hazard of Corona Resistant materials

The development of more electrical transportation systems requires rotating machines having higher efficiency and specific power. To date, this is achieved by feeding them with rising supply voltages with higher frequencies. This generalized strategy is introducing several challenges in the correct design of the insulation that is necessary for a reliable system. A major issue to be dealt with are partial discharges, an aging mechanism that can bring insulation to failure in short times. A solution often proposed by manufacturers involves the use of the so-called corona resistant materials, which supposedly can withstand partial discharge activity. This paper investigates the possibility of using corona resistant magnet wires for electrical machines operating at reduced pressures, such as the actuators for primary control surfaces in the more electric aircraft. The results show that corona resistant insulations are characterized by an improved behavior at ground level but are not a viable option at reduced pressures.