| 摘要 |
PURPOSE:To enable an unneeded switching time to be reduced by using a rush current produced when switching from a commercial operation to an inverter operation for a trigger signal for timing. CONSTITUTION:After a commercial power supply 10 of an AC electric motor 16 driven by a commercial power supply 10 is cut off, an inverter 12 which is outputting an AC voltage equivalent to a commercial power supply frequency is connected to an electric motor 16. Then, a rush current generated at that time is used as a trigger signal for timing for switching to an operation by the inverter 12. Therefore, the rush current generated when connecting the inverter 12 while outputting an AC voltage for the electric motor 16 rotating with inertial only after cutting off the commercial power supply 10 is used as a timing signal for switching to the operation by the inverter 12, thus eliminating the need for an exclusive circuit and a control terminal. |
