Phase distribution characteristics of partial discharge under square pulse voltage

With the development of power electronics, Pulse Width Modulated (PWM) power has been applied widely. The pulse voltage engendered by PWM may lead to the premature failure of inverter-fed motors. Partial Discharge (PD) under a sequence of high-frequency pulse is one of the key factors which lead to premature failure of inverter-fed motors. In this paper, aging experiment on magnetic wires for turn to turn insulation was done and partial discharge was measured, in order to understand the change propriety distinctly, the phase distribution of partial discharge under pulse voltage has been studied. The results showed that with the increase of aging time, the discharge phase becomes broad and appears discrete character. The appearance of the discharge between high phases is the symbol of faults expanding rapidly, which means an early failure of insulation.