Partial discharge measurement widely uses for insulation diagnosis as local condition. The measurement performs with a underground system with about 40 m length which consists of the GIS on the local site and transformer on the remote site.
The non-conventional method is used in this measurement, HFCT sensors are used to detect the PD pulses. After the PD measurement. There are 3 group of the PD detected, a PD group extracted from the PD cloud by the clustering tool indicates the clear corona discharge pattern.
And thanks to the localization tool, the PD source locate at the transformer site and generated on phase B due the highest amplitude of PD pulses are on phase B.
addition, the pulse polarity analysis is done to analyze the source of PD
phenomena. The HFCT has the direction which can help us separate that the PD pulse is come from out site or inside the measurement system. The HFCTs are point from the UG cable to the GIS which means if the pulse coming from the UG cable, the polarity will be positive and vise versa in case of the GIS.
On the remote site, the pulse polarity is negative but, on the local
site, the pulse polarity is positive. This can confirm that that PD pulse propagates
from the transformer to the UG cable.