| 摘要 |
PURPOSE:To reduce energy consumption in parallel operation of a plurality of feed water pumps, by controlling the flow rate by attaching an inverter to a motor for only one pump, and feeding current to other pumps directly from a power source, thereby stopping operation of the pumps or operating them under most efficient conditions. CONSTITUTION:When a switch S is turned ON, an electromagnetic switch 1C is energized and contacts 1C1, 1C2 are closed, which causes energization of an electromagnetic switch 2C, closing of a contact 2C1 and starting of an induction motor M1 and hence a pump P1. Here, output frequency of an inverter 2 is controlled by an output signal of a pressure sensor 3 such that pressure in a feed water pipe 4 is kept constant. When the flow rate of water is increased to Q.1a, a contact Q1 of a flow-rate relay 5 is closed and a contact 3c is energized, which causes closing of contacts 3C1, 3C3, 3C4, 3C5 and opening of a contact 3C2, so that a motor M1 is operated at a full speed by a power source. On the other hand, when the flow rate reaches Q2a, a motor M2 is operated at a speed controlled by the inverter 2, whereas the motor M2 is operated at a full speed when the flow rate is Q3a. |
