Design And Implementation Of Constant Pressure Watersupply Control System Without Water Tank

The constant pressure water supply system without water tank is also called non-negative pressure frequency conversion water supply system and direct water supply system?Japan?^[1].That is,the city network pipeline is connected with the water supply pipeline through buffer tank,and the city network pipeline is stored in the water tank through the tank to alleviate the impact of water,and then the water is sent to the water supply pipeline through the pump.With the improvement of living standards in the 21st century,people's demand for water supply is becoming higher and higher.Water supply equipment should consider safety and stability,prevent secondary pollution,optimize energy saving,and realize remote interconnection,remote download and remote maintenance of field equipment.In order to make the water supply system more intelligent,this system installs FBox equipment^[2]in the field cabinet and connects different types of PLC,intelligent instrument or frequency converter equipment through serial port or Ethernet port.Users can easily understand the running status and alarm of the equipment remotely through the Internet.Provide users with safe,stable and energy-saving water supply products.This project is developed independently and has diversified functions to provide sophisticated precision control,which has reached the leading level in China.The controller of water pump adopts Siemens smart PLC,and the digital output of PLC controls the contactor,and then controls the frequency conversion operation or power frequency operation of water pump.The analog output of PLC controls the frequency of frequency conversion,and inputs the acquisition value of pressure sensor.The output value constitutes a closed-loop control loop,i.e.PID control.The touch screen adopts Siemens smart700IE touch screen,which is connected with smart PLC by Ethernet mode.The reserved external communication interface adopts modbus-RTU protocol which is the most widely used in industrial applications in China.The operation process of the system requires different modules to maintain a high degree of collaboration and work together to complete the task.The introduction of the screen when the touch screen interface is realized.It is more intuitive and convenient to add the display screen to the system,and it also increases the adaptability of the system.Changing the value can be used in more occasions.At present,the water supply system has been put into use,the equipment intellectualized and fully automatic operation,no need for personnel on duty,to achieve all the design indicators,has been recognized by users.