基于PLC的污水坑水位控制系统设计

PLC（可编程逻辑控制器）是一种基于数字计算机技术、专为工业环境下应用而设计的电子系统。它具有功能强大、使用可靠、维修简便等许多优点。由于可编程序控制器安全性高、功能完善、性能稳定、应用广泛，因此，污水坑水位控制系统中的控制部分采用可编程序控制器来控制。在本系统中，采用西门子S7-200型PLC控制潜水泵的起停，其中PLC选用DC24V输入、DC24V继电器输出。污水坑水位控制系统的操作方式分为手动方式和自动方式。本课题主要任务是具备手动控制方式及自动控制方式；系统采用4台30KW水泵装置，其中3台为常用工作水泵，1台为备用水泵；设定蓄水池3档水位，从下到上依次为：停泵水位、启泵水位、报警水位。水位在停泵水位以下为停泵状态；当水位达到启泵水位，启动1台水泵排水；水位如上升至报警水位时，启动第二台水泵运行，若10s未降至报警水位以下，启动第三台水泵进行排水；当水泵温度过高或者水泵发生故障停转时，报警并处理。

 

关键词：水位控制，潜水泵，PLC

PLC (programmable logic controller) is one kind of electronic system based on technology of digital computer, and designed specially for using in industrial environment. It has many merits such as powerful function, reliable use and easy-mending. With the rapid development of microelectronic and computer technology, PLC has widely used in industrial control area. Because the PLC is safe, stable, reliable, and applied widely, the PLC is used as the controller for the sewage pit water level control system. In this system, using Simens S7-200 PLC to control the start and stop of diving pumps, in which PLC selects DC24V of input, DC24V relay of outputs, and has DC24V voltage-stabilized source. The sewage pit water level control system operating mode divides into the manual way and automatic way. This topic primary mission is the automatic control way, with 4 water level switch examining sewage pit water level, PLC according to the water level situation control the start and stop of diving pumps. To instead of past method which three pumps is working and one is for ready, the new cycle work method is applied in this design. It makes the start and stop of the diving pumps more reasonable. And at the same time, it makes the diving pumps work more efficiently and avoids to start the electric motors frequently. So the electric motor can be better protected. At the end the LAD program of the sewage pit water level control system is provided.

 

Key words：water level control, diving pumps, PLC