| 摘要 |
PURPOSE:To enable the control of the entire range of flow rate of a fan in a method, by fully opening a suction damper to control the flow rate when the rotational frequency of the fan is not lower than a lower limit, and by adjusting the degree of opening of the damper when the flow rate is not higher than a value corresponding to the lower limit to the rotational frequency. CONSTITUTION:The suction damper 12 of a fan 1 is controlled by an opening degree command signal S3 from an operation unit 13. When the rotational frequency of the fan 1 is not lower than a lower limit, the suction damper 12 is fully opened to control the flow rate of the fan. When a flow rate not higher than the flow rate corresponding to the lower limit to the rotational frequency is to be obtained, the rotational frequency is held at the lower limit and the degree of opening of the damper 12 is adjusted to control the flow rate. The entire range of discharge flow rate of the fan 1 can thus be controlled.
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