A new method for partial discharge measurement in oil-paper insulation system

In EHV power transformers, the electric charge generally appears in oil due to flowing electrification. The charge density is changed when the PD failures occur in the transformer. Therefore, the PD failures can be diagnosed by monitoring the change of charge density in the oil. Based on the above principle, research work is performed in this paper using the model of streaming electrification. In addition, the charge density is measured by use of the ACS (Absolute Charge Sensor). The experimental results from the test show that the initial discharge voltage increases and PD strength decreases with the increasing oil flow velocity. The greater the PD strength, the higher the charge density in the oil-paper insulation system. Thus, a new method for PD measurement in power transformer is obtained from these test results. Finally, the potential application in an actual transformer is suggested.