| 摘要 |
PURPOSE:To make it unnecessary to use a high-output driving means, by presetting a starting speed of rotation of a driving means at which the output is lower than the tolerable output of the driving means, and controlling the opening of a discharge valve and increasing the speed of rotation of the driving means after starting of a pump in the manner that the maximum shaft power can be obtained at the time when the pump is operated under the rated discharge rate. CONSTITUTION:At the time of starting a pump, a driving means is turned at a low speed N4 of rotation with a discharge valve being closed. The shaft power obtained at the time is P0 and the total pump head is H0. With subsequent opening of the discharge valve while keeping the speed of rotation of the driving means at N4, the shaft power is lowered gradually. When the discharge valve is fully opened, the shaft power is P3 and the total pump head is H3. With subsequent increasing of the speed of rotation of the driving means to a rated speed N1 of rotation, the shaft power becomes the maximum shaft power P1. At the time, the discharge rate of the pump is Q1 and its total head is H1. Therefore, by using a driving means having an output corresponding to the maximum shaft power P1, it is made unnecessary to employ a driving means having an excessively high output, and at the same time, the total pump head can be lowered. |
