ABSTRACT
Along with the rapid development of Chinese economy, the urbanization step is quickly. Now many people have moved to communities, so the Community has to provide good water supply quality to people, but can not waste water resources. Community built their own water systems. Community water supply system must supplies water the stability, credibility of system, the economy directly influences to supply water quality .The traditional means of water supply cover big area, and low efficiency，hard maintenance etc. So it’s already been eliminated now.
This text mainly designs a cell constant pressure water supply system, which by the PLC, transducer, water pump, pressure sensors, liquid level sensors, host computer, communication modules and other equipment composition. The system has to live tube net and fire net. The system can control by hand, it also can control automatically. It still designed a man-machine interface at the same time．Passing the long range correspondence can with the movement that the long range control the system. The system has solved the problem existing in the traditional way of water supply, such as economize water resources, it are little to throw in funds, maintenance convenience.
The system compare with the traditional way of water supply, it has energy conservation effect extraordinary prominence. For carrying out system of constant pressure, this design spreads the feeling machine examination pressure through a pressure, Then the feedback give the PID mold piece of inverter. Therefore this made one cyclic control system. And then variable-frequency controls the electric machine, so this is a variable velocity variable frequency. The problem that the thesis also discussed that the fire fight supplies water at the same time took care of to provide with the electrical engineering of two set high powers in the net in the fire fight.
Finally, it also edited and translated a man-machine interface through a set of software. The system is more perfect. At the same time we Build up a conjunction between the PLC and the computer. For the protection link, the system designed water level to report to the police, the inverter breakdown reports to the police, the soft starter protects etc.
Key words：Variable-frequency; PLC; Constant pressure water-supply; Variable Velocity variable frequency; monitor and control-system
