In this paper, we measured electric field in transformer oil / pressboard composite system, using a Kerr electro-optic method to discuss electric field distribution and charge behavior induced by flow electrification. We investigated electric field in both uncharged and charged oil, under different flowing conditions. From the experiments, we could quantitatively estimate and analyze the time transition of electric field by charge accumulation on the pressboard. Finally, we could propose charge behavior model in flowing transformer oil .

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In this paper,

In this paper, we propose a new type of phase converter that has a new configuration with a core, shading ring, a single-phase ac winding and two output windings. The induced voltages in the output windings are proportional to the fluxes that link the windings and are similar in principle to those of in a transformer. But the phase angle between the induced voltages is not equal as the flux that l i n h each output winding is not equal due to a shading effect which makes the lag. By setting the proper shading ring, 2-phase and 3-phase output voltages are obtained from the single-phase source. This new type of converter makes the induced voltages with good sine waveform because it does not contain switching elements and is not based on ferro-resonance. Experimental results show the effectiveness of the proposed structure.