Heat Exchange Station Water Supply System Design

This paper proposes a water supply system of heat exchange station with S7-224 and EM235 at the core. The analog quantity of secondary back water pipe pressure is back fed to PLC control system using EM235 module; to regulate the water supply pump motor speed the voltage signal is outputted to frequency converter by comparing the feedback pipe pressure with system setting value, which is accomplished using PID control module built in S7-224. This scheme integrate the liquid level of water tank, acceleration and deceleration of water pump motor, pool inlet water valve, reset of frequency converter and alternate operation of two circulating pump in an organic way, in which case, this system will be unattended and energy efficient. By connecting S7-224 communication port with Siemens short message module TC35 the system key data can be transmitted to manager's cellphone timely, then workers can staff responsible for running at any time. Then the use of EM277 not only add visual operation function based on touch screen, but also provide a convenient interface for a series of modern management solution, such as industry 4.0 and bus connecting network monitoring, etc.