Patent ID: 8564159

Claim:
A transformer inrush current suppression apparatus for suppressing a transformer inrush current of a circuit breaker which makes and breaks connection between an electric power system for a three-phase alternating current, including a power supply and a transformer which converts a three-phase alternating current voltage into a single-phase alternating current voltage, comprising: a transformer side three-phase alternating current voltage measurement unit which measures the three-phase alternating current voltage at a side of the transformer with respect to the circuit breaker; a residual magnetic flux calculation unit which calculates three line-to-line residual magnetic fluxes of the transformer generated after the transformer is disconnected by the circuit breaker, based on the three-phase alternating current voltage measured by the transformer side three-phase alternating current voltage measurement unit; a power supply side three-phase alternating current voltage measurement unit which measures a three-phase alternating current voltage at a side of the power supply with respect to the circuit breaker; a stable-state magnetic flux calculation unit which calculates three line-to-line stable-state magnetic fluxes of the transformer, based on the three-phase alternating current voltage measured by the power supply side three-phase alternating current voltage measurement unit; a phase determination unit which determines a phase in which phases of the three line-to-line stable-state magnetic fluxes calculated by the stable-state magnetic flux calculation unit are respectively the same in polarity as phases of the three line-to-line residual magnetic fluxes calculated by the residual magnetic flux calculation unit; and a closing unit which closes the circuit breaker in the phase determined by the phase determination unit.