Discharge Processes In Oil-Paper Insulation Defects Under DC Voltage

The existing measurement method of partial discharge(PD) under DC voltage is not perfect, and discharge processes lack diagnostic criteria. Therefore, the research on partial discharge characteristics and discharge processes under DC voltage excitation is very important for the experimental solving the problemIn this paper, a DC-PD simulation system in oil-paper insulation is built, including a discharge model, a detection system of PD, and a data acquisition system of PD. By using the combination method of constant voltage and step-up voltage, the development process of discharge at constant temperature is observed. By the method of UHF, conventional pulse current and UWB, the PD signals of development process are measured in real-time, the development process of DC discharge in oil-paper insulation is analyze.The Observed phenomena show that the frequency of DC-PD is very low, the clusters of PD happens occasionally, and PD activity enhances significantly when the voltage is changed.The results indicate that with the development of discharge, parameters including discharge frequency, average amplitude of PD, maximum amplitude of PD, and total amplitude of PD, are little changed. Therefore, it is difficult to decide the development of discharge. The TF spectrums of UWB signals can recognize the multiple partial discharge sources.