Dielectric Properties of Resin Rich Stator Coil of High Voltage Motor during Processing

One of the non-destructive test methods commonly used to characterize the electrical properties of power equipment is polarization and depolarization current testing. The objective of this paper is to study of the change of dielectric properties during the manufacturing stages of a stator coil used in 6.6 kV 260 kW motor. There were five steps to manufacture the resin rich stator coil. The first step, the copper coil was wound around by NOMEX paper. Then the slot portion of the stator coil was wound by KREMICAL tape as the second process and by the conductive tape as the third process. Then, the insulation and conductive layer of the stator coil were pressed and cured at 160°C for one and a half hour as the fourth process. The pressing and curing will combine the multi insulation to be homogeneous insulation of the stator coil. The final step, the end winding portion was wounded by Filosam tape and polyester tape. The polarization and depolarization currents were measured and recorded after finishing each manufacturing process. From the test results, the polarization currents and depolarization currents obtained from each step were clearly different. Then the polarization and depolarization currents, conduction current and capacitance of the test results were analyzed and reported in this paper.