| 摘要 |
PURPOSE:To reduce the error due to the change of a lift head, by calculating the lift head on the basis of a pump pressure, the loss of pump operation, and the difference between water levels of the pump and a water tank and measuring a pum flow rate by a stored lift head-flow rate characteristic of the pump. CONSTITUTION:The water level of a water tank 4 is detected by a water level detector 10, and a signal indicating this water level H0 is applied to an actual lift head calculating circuit 12. In case that only a pump 5-1 is operated, the pressure on the exit side of the pump 5-1 is detected by a pressure detector 11, and a signal indicating a pump discharge pressure P is applied to the actual lift head calculating circuit 12, and the loss P of pump operation is applied from a setter 13. In the actual lift head calculating circuit 12, the difference L between the water level H0 of the water tank 4 and the water level of the pump entrance is calculated, and an actual lift head h=L+P+P' is calcuated. This actual lift head (h) is applied to a flow rate converting circuit 14, and a flow rate Q0 corresponding to the actual lift head (h) is calculated on the basis of the stored flow rate-lift head characteristic. |
