Patent ID: 8779634

Claim:
A transformer inrush current suppression apparatus for suppressing a magnetizing inrush current generated by a three-phase transformer when the three-phase transformer is energized by a three-phase circuit breaker, which energizes the three-phase transformer with a three-phase power supply by simultaneous three-phase energizing, the transformer inrush current suppression apparatus comprises: a target closing phase determining circuit for calculating energization flux errors in first to third phases by changing a closing phase of the first phase within a range from 0 degrees to 360 degrees, and for determining a target closing phase which minimizes an evaluated value of the energization flux errors in the first to third phases, each of the energization flux errors corresponding to a maximum offset amount of center values of transformer fluxes generated in a static state after the three-phase circuit breaker is energized when the three-phase circuit breaker is closed; and a three-phase circuit breaker controller for controlling the three-phase circuit breaker to be closed at the target closing phase determined by the target closing phase determining circuit, and wherein the target closing phase determining circuit calculates the energization flux errors in the first to third phases based on residual flux values for the first to third phases of the three-phase transformer, a variation in an inclination of a withstanding voltage line, the variation being due to a pre-arc characteristic of the three-phase circuit breaker, a variation in closing time of the three-phase circuit breaker, and a connection condition of windings of the three-phase transformer, to which the three-phase circuit breaker is connected, while changing the inclination of the withstanding voltage line and the closing time within ranges including values the inclination of the withstanding voltage line and the closing time can have, wherein the evaluated value is a sum of the energization flux errors in the first to third phases.