| 摘要 |
PROBLEM TO BE SOLVED: To provide a mechanical power supply switch for switching power supply without having any effect on a load while avoiding overlap of power supply. SOLUTION: As first and second switches connected, respectively, with two three-phase AC power supplies, mechanical high speed three-phase circuit breakers having an opening time shorter than the current zero point interval of power supply are employed. Upon receiving an switching command externally, a controller judges open/close state of the first and second switches and begins opening operation of a closed switch immediately (S26, S42). Closing operation of an open switch is started after waiting a specified time Tw (S22, S23, S46, S47). The specified time Tw is set such that closing operation of the open switch is completed between a time point when opening operation of the closed switch completes in longest case and a time point when a maximum allowable switching time (10 ms) elapses after opening operation of the closed switch completed in shortest case. |
