Constant Pressure Water Supply System In The Water Supply Station Of The Shang Ji

With the progress development of social economic and the construct scale of city continuously enlarge, increasing of population and standard of living of people continuously improved, more and more demanding to quantity, quality and stability ofwater supply bring forward in city.The automatic degree of waterworks in town is much lower than the correspondence in city. Especially in some old waterworks, the equipment of automatic control system is dropped behind. The control of unit is mainly depended on manual operating of watches. The process of control is very complicated and that manual control can't meet the change of pressure in the pipes and the water level of the pure pond. It also can't act the proper feedback in time.For the sake of water supply, the electromotor unit usually works in the state of over charge. Not only efficiency of electromotor is low and electricity consuming is bigger,but also the pressure of pipes is overload in long term.On the basis of analyzing status in quo of the waterworks in our country, this paper designs a suit of constant pressure water supply automatic control system by using variable frequency speed-regulating technology based on PLC.The system is made up of PLC, transducer, units of pumps and electromotors, pressure sensor, industrial control computer and console. The system is used atransducer to make two electromotors starting, running and timing. The one high-power electromotors(160Kw) and low-power electromotors(90Kw) is partly circulated. To connect control computer with PLC and realize supervisal, a real time supervisal control software of water supply system is developed. The software has the function of data connection, communication, state control of facilities and data management.The operation and experiment demonstrates that the system make the work of water supply automated in some degree. It is good for energy saving and improving the management of waterworks. It's also facility to mount and maintain, reliable to operating, and precise to supervise and control. The supervisory control software has abundant functions, kind interface and convenience to using. Key Words: PLC, variable frequency speed-regulating, constant pressure water-supply, variable frequency to working frequency, phase consistency.