Electromagnetic waves from partial discharges in windings and their detection by patch antenna

The electromagnetic (EM) radiation accompanying partial discharges (PDs) in enameled-wire winding is analyzed assuming the Gaussian currents in the basic PD model. A simplified procedure is proposed to evaluate the response of patch antenna or microstrip antenna to the EM wave based on the transient circuit calculus. Analyses on the twisted pair specimen show that EM radiation from the wire currents contribute to patch antenna output much more than that from the PD itself. The analytical results are verified by an experiment on the twisted pair. It is confirmed that the patchantenna sensor is potentially capable of detecting PDs in actual motor winding.