| 摘要 |
PURPOSE:To prevent abnormal rate of rotation automatically by outputting an abnormal signal and stopping the output from an inverter when the frequency of the inverter exceeds specified frequency or more. CONSTITUTION:A pulse signal converted into pulse number required for transistor base drive control 8 by a v/F converter 7 is converted into a voltage value by an F/V converter 9. The signal is input to an abnormality detector 14. The abnormality detector 14 transmits an abnormal signal to an inverter stop circuit 13 when the input reaches a specified value or more. The inverter stop circuit 13 sends a stop signal to the transistor base drive controller 8 by the input. The transistor base drive controller 8 receives the stop signal and stops an output, and an output from an inverter 3 is stopped. Accordingly, the abnormal over-revolution of an AC motor for a turbo-molecular pump is prevented automatically. |
