Detection of Partial Discharge from Stator Coil of Rotating Machine

In order to establish the method of on-line and off-line detection of partial discharge (PD) from stator coil of rotating machine, we have researched PD characteristics and PD detection method using PD sensor and model stator coil under electrical stress and developed a new PD sensor. The PD sensor which was composed of an electrode and an amplifier could detect the PD pulse from a model coil. The phase resolved PD pattern by using the PD sensor showed the degradation type of insulation layer, for example, the existence of void between conductor and insulation layer within coil. The PD sensor is easily installed to the machine because it does not touch with the high voltage conductor. These results suggest that the PD sensor is useful for detection of PD from stator coils of rotating machine.