Evaluation of corona-resistant magnet wires through partial discharge and space charge measurements

This paper presents the results of space charge and partial discharge measurements carried out on enameled wires, specifically designed to be used in electrical motors fed by adjustable speed drives. These procedures here described can provide a useful tool for short-term evaluation of enameled wires, which can give indications also on long-term performance. Partial discharges and space charge accumulation seem to be significantly influenced by the supply voltage waveform features (frequency and shape), with an extent depending on the material itself. Moreover, partial discharge features, as pulse height and inception voltage, depend considerably on space charge accumulation which may occur, e.g., with unipolar waveforms. Both techniques provide considerably different fingerprints of the two tested kinds of wires.