Abstract
Now, vast majority of urban residents use solar water heaters, so do a considerable
number of rural people. Solar water heaters are technically more mature, relatively low cost.
Meanwhile, since it provide absolute security to the people of hot and people are welcome,
and it has some advantages of energy saving, environmental protection, safety, convenience,
long, etc. So it will be widely applied. Therefore, the research and development of controlling
system of advanced solar water heater are becoming increasingly important.
This design expounds the application of PLC in solar water heater automatic controlling
system, especially the designing process of hardware and software of the system. Furthermore,
the project shows that the key of PLC designing is to satisfy the basic controlling function,
considering the convenience of maintenance and scalability. In this design, the address of I/O
is resigned and the suitable PLC is chosen. The electrical principle diagram and the
interconnection diagram are drawn, according to the requirement. Automatic water drainage,
automatic cycle, automatic heating, PID loop control temperature water, manual and
automatic mode switching function have been realized. And on this basis, the system was
simulated using the simulation software for S7-200, produced a man-machine interface by
using WinCC Flexible software. As the controlling system of solar water heater, PLC greatly
reduces the number of other components. Moreover, it has the feature such as simple
interconnection, rapid and easy fault detecting and maintenance, and advancement of the
system.
The paper is divided into four chapters: the first chapter describes the background of the
development and design of solar water heaters significance; Second chapter describes the
working principle of solar water heaters; Third chapter describes the hardware selection and
system processes; The fourth chapter describes the procedures for the preparation of the
system, system simulation, HMI (WinCC Flexible) configuration process.
Keywords: Solar water heater; PLC; Automatic control system
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