In some small and medium-sized factories, it is necessary to conduct centralized treatment of the discharged sewage. Therefore, we choose to make a sewage pond and set up three sewage drainage pipes, and then put them into the small sewage pump, the large sewage pump and the standby sewage pump.
Set four limited liquid level of the liquid level of the sewage pond:
1: ultra low level, no sewage pump work, liquid level alarm light;
2: low level, small sewage pump work;
3: the higher the level of work, large sewage pump;
4: ultra high liquid level, two sewage pump work at the same time, liquid level alarm light light.
When a sewage pump fails, another sewage pump works automatically, and the fault alarm light is lighted.
When all two sewage pumps fail, the spare sewage pump works automatically and the fault alarm light is lit.
The control aspect of this design is implemented by SIEMENS PLCS7-200, and the simulation software is used to carry out live simulation. Key words: Sewage treatment system PLC control small and medium sized enterprises to discharge sewage
