Feasibility of partial discharge detection in inverter-fed actuators used in aircrafts

Partial discharge measurements performed on varnished coils (motorettes) subjected to both repetitive square and sinusoidal voltage waveforms at reduced atmospheric pressures are presented. The aim of the investigation is understanding whether partial discharge monitoring of commercial aircraft actuators is feasible or not. The result show that, provided that airplanes do not flight at altitudes above 10 km, partial discharge detection is feasible using the UHF techniques. Also, it is found that, for varnished coils, the lower discharge voltage limit provided through the Paschen curve provides a conservative estimate of the partial discharge inception voltage and can, therefore, be used as a basis for insulation system design.