| 摘要 |
PURPOSE:To prevent an inverter from becoming abnormal overcurrent by starting a freely running AC motor by an inverter when the sum of rotating frequencies of a plurality of freely running AC motors becomes the output frequency of lower capable of starting the predetermined inverter. CONSTITUTION:When an inverter is stopped so that a contactor 6 is opened, AC motor group become free running state, and the rotating frequencies FM1- FMn of the free running state decreases as time goes. When restarted by the inverter, the sum FM of the output frequency fINV of the inverter and the rotating frequency is compared and calculated, and the inverter is started when becoming the sum FM lower than the output frequency fINV (c). Thus, the inverter can be stably started. |
