Partial discharge analysis through Lissajous figure at low air pressures

The condition of electrical insulation is significant to the safety of electric power systems, especially to the More Electric Aircraft (MEA) that carries hundreds of people. The property of insulation will be reduced by aging and degradation which caused by partial discharge (PD). This has become a topic of extensive research and investigation. This paper represents the PD detection in terms of Lissajous figures which is a composite of two orthogonal oscillations with integral proportional frequencies. It can be used to calculate the total charge of PD transferred per cycle and the total energy of PD per cycle, thus the average charge and energy of a single PD activity can be recognized accompany with the current pulse PD detection method based on IEC 60270. These parameters could be useful to evaluate whether the insulation was damaged or how badly the damage was, hence to provide references to engineers for insulation condition judgment and design service plan.