A new technique to mitigate inrush current caused by transformer energization

This paper presents a new method to mitigate inrush currents caused by transformer energization. The method uses a grounding resistor connected at the transformer neutral and delayed energization of each phase of the transformer. The proposed method was tested by PSCAD/EMTDC simulation and laboratory experiments. Both simulation and experimental result show that the proposed scheme has a performance similar to that of the resistor pre-insertion scheme, but it will be much less expensive since there is only one resistor involved. The level of the inrush current reduction depends of the value of the neutral resistance and of the transformer parameters.