Interpretation of Partial Discharge Quantities as Measured at the Terminals of HV Power Transformers

The paper discusses the application of signal processing techniques in the interpretation of partial discharge (PD) pulses as detected at the terminals of power transformers. Special consideration is given to the concept of PD energy and to the effect of waveshapes. Examples are included of FFT analyses of PD waves as stored in digitized transient recorders during HV tests. The possible relevance of the frequency spectra in the assessment of dielectric damage is considered, together with associated circuit effects. A predominant factor in transformer testing is still the need for satisfactory PD location methods: a description is given of experimental techniques using conventional discharge detectors and a computer-based measurement system.