| 摘要 |
PURPOSE:To improve the reliability of a system by changing over an operation from inverter operation to the operation by a commercial power source when only one of two six-pulse inverters gets trouble. CONSTITUTION:When a twelve-pulse inverter 7 gets trouble, a sound six-pulse inverter is operated by a six-pulse inverter control circuit 12 while a signal closing a damper is output to the damper 11, and the load of a load machine is lowered. When the load of the load machine 10 is reduced and an operation- frequency feedback signal 24 at the time of six-pulse operation is equalized to the frequency of a commercial power, the six-pulse inverter control circuit 12 is controlled by a commercial synchronous control circuit 18. When the output voltage and frequency of the six-pulse inverter are synchronized with the commercial power source, a commercial synchronous signal 25 is output to a switch 3 from the commercial synchronous control circuit 18, and a synchronous motor 9 is changed over to the commercial power source operation. |
