| 摘要 |
PROBLEM TO BE SOLVED: To prevent the lowering of water supply pressure generated right before additional driving by difference in actual Q-H characteristics inherent in a pump itself by performing the pump additional driving at a time when it reaches the water supply quantity obtained by subtracting overall allowance totaling respective flow control allowances under driving at present together. SOLUTION: In controlling the driving number of a plurality of water feed and supply pumps installed in a water feed and supply station, an additional driving changing from a single driving to two pumps driving is performed, when the water feed and supply quantity reaches a value (Q1-ΔQ1) obtained by subtracting a difference quantityΔQ1, a difference between a characteristic curve inherent in the first pump, or a characteristic curve by pump secular change and a typical characteristic curve (1) from the water feed and supply flow rate Q1 corresponding to a constant water feed and supply pressure on the typical characteristic curve (1), when the first pump is driven at rating rotation speed. The additional driving from two-pump driving to the three-pump driving is so controlled to perform similarly when the water feeding and supply quantity reaches (Q2-ΔQ2) from the water feed and supply flow Q2.
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