Time Domain Detection of Partial Discharge in Current Transformer

The partial discharge test is an efficient technique for detecting early failure of high-voltage equipments. Depending on the application, it is possible to use acoustic, optical or electrical methods. For electrical detection, the UHF method is widely used for PD measurements. For the noise issue, this method is more sensitive than other methods. However, the UHF antenna is often installed at a specific location near the device under test (DUT), so it is difficult to detect the PD at all locations with the same sensitivity. In this study, we use RF coils to detect the radiating frequency (RF) from partial discharge. Two RF coils installed at two surfaces of the current transformer are used to pick up the partial discharge. From the amplitude and the occurrence of the PD signal on the time scale, we can locate where the partial discharge occurs. The spread of the PD signal is explained by a one- dimensional propagation model.