| 摘要 |
PURPOSE:To prevent surging by a method wherein a gate is not conducted when an air release objective value is lower than a low level value to close the air release valve fully in order to prevent the air release valve from unstable opening and closing operations being effected in the low level range of the air releasing amount. CONSTITUTION:When the gate 9 is not conducted, the air release objective value signal of an adjusting meter 8 is cut, therefore, the air release valve 6 is controlled to close it totally. Accordingly, the valve opening motion pattern of the air release valve 6 opens the valve by a predetermined opening degree only in an operation zone in which the air releasing amount QB is higher than a specified value and, especially, does not effect the unsatable full-opening or slight-opening of the valve in a zone in which the air releasing amount QB is lower than the low level value L and, therefore the air release valve 6 may be kept in the totally closed condition thereof. Thus, the surging of the fan may be prevented under stabilizing the control motion of the release valve. |
