Comparison of Insulation Capability of Round Wire and Hairpin Windings by Partial Discharge Measurements

In this paper, the reliability of different windings of electrical machines is analyzed using partial discharge measurements. The focus is on the comparison between round wire and hairpin windings. In addition, round wire windings with different degrees of insulation are compared. The measurements were performed on self-developed motorettes, which have insulation systems of real machines. The partial discharge measurements are performed both between the windings and between the winding and the stator core to investigate the slot and the end winding areas. The results show a superior partial discharge behavior of hairpin windings compared to round wires. In addition, the end winding could be identified as a weak point compared to the slot area.