Partial discharge measurement and localization in 115kV, 50 MVA Power transformer in Cambodia

In May, 2022, Paralec has been contacted to measure the PD activity of power transformer. Such transformer has been suspect the PD activities inside by DGA method, the gas contents increased over  the months.

First, BlueBox technology, MS Pico was carried out for PD measurement. The PD level, PD pattern, PD pulse shape,  PD evolution are observed. Thanks to unique BlueBox technologgy, the small PD pulse can be extracted from the noise which a challenge of field measurement. 

The measurement results show the PD activity on phase B. Thanks to the voltage reference taken from phase A of OLTC, PRPD indicate the surface discharge due to the carbonize track or corona discharge. Regarding to DGA analysis, there is a thermal fault and the increasing of CO gas which indicates that there is a degradation of the paper.

As the polarity is the same in all three measurement channels, it can be ensured that all three PD activities are coming from the transformer and are affecting all three phases.

Second, after the PD activities are conformed, to do the maintenance properly and straight to the PD source when the transformer is opened, the PD localization was made by AE-150.  Thanks to the AE-150, with 4-acoustic sensors and HFCT sensor, the PD source can be localized in 3D.