Electromagnetic Waves from Partial Discharges and their Detection using Patch Antenna

The electromagnetic (EM) wave generated by partial discharge (PD) is analyzed using electric dipole model. The pulse electric and magnetic fields are described by analytical functions. The interaction of patch antenna or microstrip antenna with the EM wave is investigated on EM theory, which leads to a simple transmission-line model. Then, the response of patch antenna to the PD-initiated EM wave is numerically analyzed as a circuit transient. It is found that the generated EM fields and the response of patch antenna strongly depend on how fast PD develops. The sensitivity of patch antenna to PD is expressed in a simple chart. The analytical results are verified by an experiment in which the EM wave from a short-gap discharge is detected by the patch-antenna PD sensor. The patch-antenna system is expected to be used for detecting PDs occurring inner parts such as winding's inter-turn.