Magnetizing inrush current suppression device and method for transformer

Abstract

To suppress the magnetizing inrush current occurring when supplying power of three phases of the transformer are performed simultaneously using three single-phase circuit breakers or a non-phase segregated operation-type circuit breaker, without providing a circuit breaker with a resistor or other equipment. A magnetizing inrush current suppression method for transformer suppresses a magnetizing inrush current occurring at the start of energizing of a three-phase transformer, when a three-phase power supplyis input to a terminal of each phase by means of a three-phase circuit breaker. In the method, by integrating phase voltages or line-to-line voltages on the primary side or the secondary side or the tertiary side when three-phase AC voltages are applied in a steady state to the transformer, steady-state magnetic fluxfor each phase of the transformer is calculated, and the polarity and magnitude of the residual magnetic fluxof each phase of the transformer after the circuit breakershuts off the transformer are calculated, and the three-phase circuit breaker is caused to close simultaneously in a regionin which three phases overlap, each of the three phases having the polarity of the steady-state magnetic fluxequal to the polarity of the residual magnetic fluxfor each phase of the transformer.