An investigation on PRPD patterns generated by the UHF measurement technique for power transformers

In this contribution, the alternative approach of applying the PRPD technique to the captured UHF signals in order to obtain an UHF PRPD pattern as a complementary tool for PD root cause analysis is investigated. For this purpose, different fault scenarios were created inside a specially designed transformer tank. The UHF signals were captured via different antennas using several measurement setups to determine how parameters such as frequency, bandwidth, PD location, etc. affect the sensitivity of the UHF measurement technique for different types of PD. Furthermore, the correlation between the captured PRPD patterns using the electrical measurement according to IEC 60270 and the UHF measurement technique were analyzed and compared. Finally, the results are presented and the advantages and flaws of the PD cause identification via the UHF PRPD technique are discussed.