Study on the On-line PD Measurement Technology for Power Transformer

Since partial discharges weaken the insulation performance of power transformers, the detection of PD is very important for prevention of fatal incidents. This study describes the use of electromagnetic coupler for the partial discharge measurement of transformers. Folded dipole antennas were used as sensors and installed in test chamber for experiments. The spectrum and oscillogram measured in various defect cells are analyzed and showed. And these partial discharges signals are measured at the same time by two types UHF amplifiers with different bandwidth and a conventional PD detector. From these results, decision of defect type is available