Sensitivity verification and determination of the best location of external UHF sensors for PD measurement in GIS

Partial discharge detection is the most effective method to monitor and diagnose the insulation condition of high voltage apparatus. UHF method becomes more popular because of its higher S/N ratio. UHF sensors are the most important part of UHF method PD measurement. This paper deals with the PD measurement using several UHF sensors installed on 66 kV GIS model with needle protrusion on the conductor as its PD source. Sensitivity verification for external UHF sensors were examined based on CIGRÉ Task Force 15/33.03.05 to ensure that the sensors can fulfill the minimum requirement for PD measurement in GIS. Then, the effects of sensor position in the circumferential and effect of the sensor distance to PD source on PD magnitude were measured by the external UHF sensors. Result of this experiment are compared with simulation using FDTD method. Finally, based on this result, we recommend the best position of external UHF sensor applicated on GIS.