| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power supply switching device which switches a plurality of ac power supply, in a practical manner without uninterruptible disconnection, and suppresses changes in the power supply frequency to be within a predetermined range, with hardly deviations in the waveform at switching. <P>SOLUTION: In the power supply switching device, semiconductor switches 1a, 1b are connected between each ac power supply and the load, and the device includes a frequency-detecting means 12 for detecting the frequency of the ac power supply; a phase difference detecting means 13 for detecting the phase difference between open side power supply and turn-on side power supply; and a switching control means 14, which switches the open side power supply to the turn-on side power supply for controlling opening and closing of the semiconductor switches 1a, 1b, when the frequency of the turn-on side power supply lies within the predetermined range to the frequency of the open side power supply, and the phase of the turn-on the side power supply and the phase of the open-side power supply match substantially. <P>COPYRIGHT: (C)2007,JPO&INPIT |
