| 摘要 |
<p>PURPOSE: To stabilize a water level of a pump well by reducing its starting- stopping frequency without performing variable speed control on a pump. CONSTITUTION: A pump means composed of pumps 21 to 23 and delivery valves 61 to 63 is arranged as a discharge means from a pump well 1, and the delivery valves are formed as a structure that opening can be switched in plural stages, and a control device 4A restrains a rise fall in a water level by raising-lowering an opening step of the delivery valves in a pump starting condition when the water level rises, and controls starting-stopping of a pump for the first time when the device cannot cope with it under discharge quantity control by these delivery valves. Therefore, the water level is stabilized while reducing a staring- stopping frequency of the pump. The fact that the water level of the pump well is going to suddenly rise like heavy rain time is also anticipated from a rate of change in the water level, and a sudden rise in the water level is restrained by this anticipation by immediately raising the opening step by a single stage without waiting a rise of the opening step of the delivery valves for a specific time.</p> |
