Transient Electric Field Analysis in Consideration of the Electric Field Dependence of Resistivity in the Converter Transformer

Abstract

In this paper, values of the electric field in the pressboard and oil during the polarity reversal test of the converter transformer were calculated with transient analysis. First, we confirmed the accuracy of the non-linear analysis in the model test. Next, we carried out non-linear transient electric field analysis for polarity reversal test of the converter transformer. In the results, when the applied time of DC voltage before the polarity reversal is 360min, the values of the electric field of oil are the same as when it is 90min. Although, the electric field in the pressboard becomes higher in response to the applied time of DC voltage, it does not cause a problem on the insulation. Because withstand voltage of pressboard is very high. In the results, the correlation between the applied time of DC voltage before the polarity reversal and the withstand voltage of transformer is considered low. This result can be applied to the design of the converter transformer.