| 摘要 |
PURPOSE:To judge whether or not natural outflow is proper by calculating the possible natural outflow from the rotational frequency of a pump or the opening of a valve and the actual outflow. CONSTITUTION:The rotational frequency of a pump is controlled by a controlling device 12. The lift curve of the pump in the rated rotational frequency of the pump can be approximated by a secondary curve. The lift curve of the pump in varying the rotational frequency can be calculated since the lift and the flow are respectively proportional to the square of the rotational frequency and the rotational frequency itself, and the lift can be calculated from the flow and the rotational frequency since the lift curve is a function of the rotational frequency and the flow. Thus, as the lift of the pump is calculated from the lift curve, water-supply flow and measured rotational frequency value of the pump, it is found that the pump needs to keep running if the lift of the pump is positive and natural outflow becomes possible if it is zero of negative. |
