| 摘要 |
PURPOSE:To omit the labor hour of once stop and restart, and to return rotational speed to original one by directly inputting a set frequency command to a control circuit without through an adjustable-speed computing element at the time of the recovery of service power and gradually rising a voltage command from zero when service interruption exceeding a fixed time is executed to an AC motor during operation at inverter set frequency. CONSTITUTION:In an induction motor (I) 5 driving load having a large flywheel effect, revolution is continued even when service interruption is continued for a time exceeding a fixed time, and operating speed is returned to original one immediately after the recovery of service power. Since a signal from a frequency setter (F) 9 is input to a control circuit through an adjustable-speed computing element (S) on the driving of (I) 5, AC voltage and frequency from an inverter to (I) 5 are increased gradually. When service interruption is continued for the time exceeding the fixed time, a logic element 8 is operated, and the set signal of the F9 is input directly to a service-interruption recovery-time control circuit 6 without through S while a voltage command value in specified functional relation to the control circuit 6 is also risen from zero gradually, thus smoothly recovering revolution to set frequency speed quickly in (I) 5. |
