目 录

1 概述..............................................................................................................................1 1.1变频恒压供水产生的背景和意义 ..............................................................................1 1.2变频供水系统的发展趋势 ........................................................................................3 1.3 本文主要内容 .........................................................................................................3 2 变频恒压供水系统构成及工作原理 ..............................................................................3 2.1系统的构成 ..............................................................................................................5 2.1.1执行机构 ............................................................................................................5 2.1.2信号检测 ............................................................................................................6 2.1.3控制系统 ............................................................................................................6 2.1.4通讯接口 ............................................................................................................7 2.1.5报警装置 ............................................................................................................7 2.2工作原理..................................................................................................................7 2.3 变频恒压供水系统中加减水泵的条件分析 .............................................................8 2.4主电路接线图 ..........................................................................................................9 3 基于PLC的变频恒压供水系统设计与实现 .................................................................10 3.1控制要求................................................................................................................10 3.2 变频器的选择与接线 ............................................................................................10 3.3压力传感器的接线图 .............................................................................................12 3.4 原其它元器件的选择 .............................................................................................13 3.5 PLC控制I/O口配置 .............................................................................................15 3.6 电气控制系统原理及线图 .....................................................................................16 3.6.1主电路图 ..........................................................................................................16 3.6.2控制电路接线图 ...............................................................................................16 3.7基于PLC的变频恒压供水系统程序流程 ................................................................18 3.8控制方式................................................................................................................20 3.8.1 手动运行 .........................................................................................................20 3.8.2 自动运行 .........................................................................................................20 3.9主要程序说明 ........................................................................................................21