| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a hoist machine having a simple constitution, capable of returning most regenerative power of a hoisting/lowering motor in the lowering operation to a commercial AC power supply side, while maintaining a function, such as a gradual stop which is characteristic of an inverter driven hoist machine, and to provide a method for switching a power supply of the hoist machine. <P>SOLUTION: In a control device 13, an inverter 11 is operated, in a state where the output frequency thereof is deviated more than that of a commercial AC power supply 10 by a predetermined amount, when shifting from an accelerating lowering operation to a high-speed lowering operation is performed in lowering operation, or shifting from a high-speed lowering operation to a decelerating lowering operation is performed in lowering operation; and a switching function is provided which switches a power supply of the hoisting/lowering motor 12 from the commercial AC power supply 10 to the inverter 11 (electromagnetic switches 18, 19) or from the commercial AC power supply 10 to the inverter 11 via power supply switches, when the output of the inverter 11 and the commercial AC power supply are synchronized by a phase detection signal S1 detected by a phase detector 17 and a phase signal S5 from the inverter 11. <P>COPYRIGHT: (C)2009,JPO&INPIT |
