Patent ID: 9082562
Filing Date: 2015-07-14
Classification: H01H,H02H

Abstract:
1. An inrush-current suppressing device, applied to a configuration of supplying and shutting off a three-phase alternating-current power supply to and from a three-phase transformer via a three-phase circuit breaker, for suppressing a magnetizing inrush current possibly generated in the three-phase transformer during actuation of the three-phase circuit breaker, the device comprising: a residual-magnetic-flux calculating unit that calculates a residual magnetic flux in a reference phase of the three-phase transformer while assuming a maximum magnetic flux level generated at a time of applying a rated voltage as 1 PU based on voltages applied to the three-phase transformer before and after opening the three-phase circuit breaker; a stationary-magnetic-flux calculating unit that calculates a stationary magnetic flux in the reference phase of the three-phase transformer with reference to the maximum magnetic flux level obtained as the 1 PU based on voltages applied by the three-phase alternating-current power supply to the three-phase circuit breaker, in response to a closing command to the three-phase circuit breaker; and a control unit that actuates a switch of the three-phase circuit breaker corresponding to the reference phase at a timing when the stationary magnetic flux in the reference phase calculated by the stationary-magnetic-flux calculating unit matches the residual magnetic flux in the reference phase calculated by the residual-magnetic-flux calculating unit, in response to the closing command.