| 摘要 |
PROBLEM TO BE SOLVED: To provide a phase-control switching device for controlling an opening-closing operation of a breaker so as to set a difference between residual magnetic flux of a second input phase and that of a third input phase nearly zero even immediately after inputting a first phase when each three-phase breaker is opened and currents of all the three phases are cut off at the same time. SOLUTION: Respective contacts for three phases in each arc-extinguishing chamber of each breaker 50 are opened at a zero-voltage point of any of the three phases at the same time. When each three-phase breaker 50 is opened and the currents of all the three phases are cut off at the same time, the residual magnetic flux levels of the respective phases of a transformer 10 can be controlled so that the residual magnetic flux level of the phase cut off at the zero-voltage point is maximized (for instance, -2K or +2K) and the residual magnetic flux levels of the other two phases are set to the residual levels opposite to and at intensity nearly half as much as the residual magnetic flux level of the phase cut off at the zero-voltage point and nearly equal to each other (for instance, +K and +K or -K and -K), whereby the difference between the residual magnetic flux of the second input phase and that of the third input phase immediately after inputting the first phase can be set nearly zero by first inputting the phase cut off at the zero-voltage point. COPYRIGHT: (C)2006,JPO&NCIPI |
