| 摘要 |
PURPOSE:To make uniform the numbers of starting cycle times of pumps and the operating times thereof, by regarding all speed control pumps as constant speed pumps, excepting one of them, and by stopping at an earlier time a pump which has been started at an earlier time. CONSTITUTION:A speed control is made such that a first pump well 3 is operated at its minimum speed at its starting water level while it is operated at its maximum speed at an additional starting water level. When two speed control pumps are operated upon additional pump starting operation, a speed control pump discriminating circuit 10 operates the pump which is operated at present as a speed control pump, at a constant speed, and the additional pump is used as a speed control pump. Further, the pump which has been started at an earlier time is stopped at an earlier time. With this arrangement, the starting frequencies of several pumps and the operating times thereof, may be made to be uniform.
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