Flow Electrification Characteristics of Oil-Paper Insulation under DC Voltage

In order to study the effect of space charge on oil flow electrification under DC voltage, an experimental model with plane electrode was designed. A closed oil circulating system was built to simulate the oil path between the windings inside a converter transformer. The results reveal that polarity of streaming current depends on the sample configuration. If the high voltage electrode was covered, streaming current was positive. Otherwise streaming current had a tendency to be negative as applied voltage increased. With the increase of applied voltage amplitude, the streaming current was always enhanced. Amplitude of streaming current was related to the number of pieces of craft papers placed under electrode. More craft papers placed under high voltage electrode led to the increase of streaming current. This result is in accordance with the experiment of space charge behavior in the sample with two layers of oil-immersed-paper and oil.