Reduction of Measurement Fluctuation of Partial Discharge Inception Voltage for Inverter-fed Rectangular Wire Motors

Summary

In this research, we investigated the factors which affect PDIV fluctuation between the coil wires under a sinusoidal voltage by using a rectangular wire motor (AIW coating, thickness 40µm) in which the neutral point is unconnected. Experimental results revealed that PDIV under low humidity environment fluctuated at the initial period of pre-discharge, whereas PDIV under high humidity environment increased transiently after the pre-discharge. Furthermore, the PDIV transition under high humidity environment decreased at high measuring frequency, which is not influenced by the absorbed moisture in the coating. To clarify their mechanisms, we performed surface charge measurement and electric field analysis taking account of the change in surface conductivity of coating with a water adhesion. As the result, we found that the PDIV fluctuation under low humidity is affected by the surface charge, and the PDIV transition under high humidity can be explained by the change in electric field strength in the air gap between the coil wires. From these analyses, we proposed the measurement method of PDIV with a low fluctuation and transition for the rectangular wire motors, which will be optimized by environmental humidity, pre-discharge condition and measuring frequency.

Additional informations

Authors

Wakimoto Toru, Wimmer Rene, Psotta Torsten