| 摘要 |
PURPOSE:To enable the terminal water supply pressure to maintain approximately constant by providing pressure sensors, means of driving pumps, and variable- speed command control unit and operating the pumps with variable speed in accordance with the resistance curve of the water supply pipe line for the pumps. CONSTITUTION:As a pump operation control means and a variable-speed command control device, the output side of an inverter unit INV is connected to induction motors M1 and M2 for pumps P1 and P2 through variable-speed operation switches MC2 and MC3, and the motors M1 and M2 are also connected to an AC power source PW through constant-speed operation switches MC1 and MC4 respectively. When a pressure sensor PS judges that the water-supply pressure is lower than the target water-supply pressure predetermined along the water supply pipe line, the pumps being stopped or being operated are started or accelerated. When the pressure is higher than the target water supply pressure, the pumps being operated are decelerated or stopped, and kept waiting for longer than the time required for starting, stopping, or varying the speed of the pumps, thereby allowing the terminal water supply pressure to be maintained approximately constant. |
