| 摘要 |
PURPOSE:To continue operation at once even if one phase out of three phase ac power sources is lacked, by installing an open-phase detecting means, a open-phase time operation command means, and a second inverter converting alternating voltage out of a converter into an input power source of a transformer, respectively. CONSTITUTION:Supporting that R phase out of three phase ac power sources is lacked, by way of example, a signal of an open-phase detecting means 9R is transmitted to a control means as L. A signal passing through a NOT element 15 comes to H, being inputted into an AND element 17, and an H signal out of an open-phase detecting means 9T or T phase is also inputted into this AND element 17, and the output comes to H. Accordingly, an H signal out of an OR element 20 is outputted, whereby a second inverter 11 operates. At this time, this H signal out of the OR element 20 is inputted into an open-phase time operation command means 10 as well, and with the inverter 11 operated, a voltage detecting relay 12 is energized with current, and normally opened contacts 121a, 122a are closed, then voltage is impressed to a transformer 13 from the inverter 11 by this selecting means 23, thus it is restored to a state before phase lacking. |
