Constant Pressure Water Supply System Design Based On Siemens Plc Controller

With the rapid development social economy, on one hand, people's request to enhance the quality of water supply and the water supply system reliability is increased continuously, for the other hand, there is also a great pressure of the insufficient water and electricity supply. In the traditional watering devices, the selection of water pump is often determined by the maximum capacity of water supply, but the actual water output is changed all the time. As a result, the water supply pressure is unsteady and the water pump efficiency turns to be low, which finally causes the waste of water resources. Under such circumstances, a better designed water supply system is needed. By using the advanced automatic control technology, the computer technology, people can design a kind of high performance and high energy conservation constant pressure water supply system that can be adapted in different areas.The design of the system is the VF water supply systems that controlled by PLC of Siemens S7-200 series. The paper introduced the principle of energy saving, system structure and working principle of this control system. By the logic control of PLC, pressure adjustment of the frequency converter, operation of PID, PLC controls the switchover between variable frequency and power frequency, which automatically makes the closed-loop adjust constant pressure and conduct the variable water supply. Of the system design, it gives a comprehensive introduction of hardware system configuration, selection, software system process design, and process design. It also points out the problems that existed in design process and gives the related solutions.The constant pressure water supply system has good performance in real-time water pressure control. The hardware module is stable and reliable. The control mode of frequency converter is analog quantity input and through the PID order to realize valid control of closed loop, which achieves the control requirements of water supply system and satisfies the work and daily water needs of urban residents.