Dependences of partial discharge characteristics fo enameled magnet wires on applied voltage waveforms

Summary form only given. Dielectric barrier discharges (DBDs) can be generated by a simple electrode configuration in atmospheric pressure, so that it can be used to various applications such as plasma sterilization1. On the other hand, major research effort is now being devoted to partial discharge (PD) activities in motor windings since a transient surge voltage induced by the switching of IGBTs has been considered as a critical issue for electrical insulation of inverter-fed random wound motors. It is noteworthy that nanocomposite enameled wires, in which nano-sized inorganic material such as layered silicate is added in conventional organic insulating material, have been developed in order to improve insulation capabilities of motor windings. We have investigated effects of ambient temperature and humidity on PD characteristics in twisted pairs with nanocomposite enameled wires by comparing those of conventional enameled wires2. The observed PD phenomena have been discussed in terms of material characterization of the enameled wires such as changes in permittivity due to moisture absorption and wettabilitiy under voltage application. In our previous experiment, an ac voltage of 60 Hz was applied to the twisted pairs. We have recently started to investigate dependences of PD characteristics on the applied voltage waveforms (frequency, unipolar or bipolar, etc.). In the conference, PD characteristics with an impulse voltage application simulating an inverter surge will be also discussed.