Source characterization of discharges in transformers using UHF PD signatures

UHF patterns of discharges representative of that occurring in a transformer were recorded by simulating them in a 220 kV test tank. The influence of the location of the UHF sensor, type of barrier and partial discharge (PD) magnitude on UHF sensitivity was studied. Information concerning the temporal development of discharges, their location, type and severity were also obtained. Classical PD patterns were recorded alongside for comparison. Experimental studies show that source characterization of discharges is possible when stable discharges can be obtained. The effect of different UHF PD measurement system and signals acquisition parameters on UHF PD detection sensitivity and acquired patterns have been studied and found to have a strong influence.