| 摘要 |
PURPOSE:To ensure a wide range of control for the ventilation value supplied by driving successively a blower controlled by an inverter and other plural blowers set in parallel to each other in response to the requested ventilation value. CONSTITUTION:A controller 22 controls a blower 18a and blowers 18... based on the detection output of a dissolved oxygen detector 24. In this case, only the blower 18a is controlled by an inverter controller 20 and supplies the air into an aeration tank 10 if the ventilation value requested by the detector 24 is larger than the lower limit value of the inverter control and smaller than the upper limit value of ventilation of the inverter control blower 18a. When the requested ventilation value is larger than the upper limit value of ventilation of the blower 18a, the ON/OFF control blowers 18 are driven by the controller 22. Then the blowers 18 and 18a send the air into the tank 10. Thus it is possible to satisfactorily cope with the requested ventilation value.
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