Optimal frequency selection for detection of partial discharges in power transformers using the UHF measurement technique

Electromagnetic (EM) wave propagation in the ultrahigh frequency (UHF) range, generated by partial discharges (PD) is widely employed for monitoring and diagnostic purposes in the field of gas-insulated substations for over a decade. For power transformers, this is a far more demanding challenge due to their complex inner structure. In this contribution, the application of the UHF measurement technique in power transformers is studied. Various influencing parameters on this special use case of sensors for PD measurements are discussed from an EM standpoint. Consequently, a practical approach towards determining an appropriate center frequency and bandwidth for performing UHF measurements depending on the test object is proposed and validated using practical measurements. •Application of the UHF measurements technique in detection of partial discharges (PD) in power transformers.•Practical approach to selection of the optimal frequency range based on the test object for performing UHF measurements.•Potentials of this method in the classification of the type of PD.