PD pattern recognition in transformer by using UHF technology

We have designed 5 kinds of partial discharge (PD) models to simulate typical PD faults in transformers. We have measured these PD models in our laboratory by using both our UHF measuring system and a conventional PD measuring system. The results detected by the UHF-system indicated, that PD patterns of a specific PD-defects could be identified clearly from their power spectrum. The statistical distribution of PD-signals like Q_Max∼φ, n∼φ obtained from the UHF transient signal envelops show different distributions for different PD faults. These statistical distributions are consistent with the well-known results obtained from the conventional PD measuring system by other scientists.