| 摘要 |
PROBLEM TO BE SOLVED: To improve the disadvantage of the conventional pump whose rotation al number at rated flow and declared power is set up as a maximum revolution per minute, that is incapable of full utilization of pump performance and difficult to expand the versatility and leading to low economical efficiency of machine and running cost. SOLUTION: In order to make the pump operational within the range of the pump maximum capacity curve 38, the pump is controlled using a provisional maximum rotation number Nmax as the pump rotation number Nc where running current value I matches with declared current value Ic with zero discharge flow after power is applied to the feed water unit. This is applied for the pressure set value Ps is changed. During pump operation using pressure set value Ps as P1, pump rotation number Nx when limiter of motor driven circuit is actuated or equivalent pump rotation number asα×Nx (whereα≈1.0,α<1.0) is memorized on memory and in next pump start-up operation, the pump is controlled by renewing the maximum rotation number Nmax asα×Nx.
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