A new method for transformer protection based on the ratio of voltage and fluxional differential current

In order to resolve the mal-operation in transformer differential protection causing by magnetizing inrush, the limitations of magnetic flux characteristics principle is introduced first, then this paper is to put forward a new method for distinguishing magnetizing inrush based on the ratio of voltage and fluxional differential current. The principle is simple and its implementation is easy. None of anticipated internal parameters is needed. The advantages of the method are convenient data acquisition, quick calculation and operation. The results of simulation testing confirmed that the method is able to clear the internal fault reliably and quickly. Therefore, this method has great practical value.