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140DDM69000工控备件PLC模块卡件

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140DDM69000工控备件PLC模块卡件

类目:140系列PLC
型号:140DDM69000
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140DDM69000工控备件PLC模块卡件 140DDM69000工控备件PLC模块卡件 140DDM69000工控备件PLC模块卡件
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140DDM69000工控备件PLC模块卡件 140DDM69000工控备件PLC模块卡件

140DDM69000工控备件PLC模块卡件
用来指明控制环的起始地址;操作数LOOP是控制环号(常数,0~7)。编号为2、4、5、6、7的参数固定不变,可在PLC主程序中设定;编号为1、3、8、9的参数具有实时性,须在调用PID指令时填入。

由于S7-200输入和输出为开关量,而变频器、压力变送器和振动变送器的信号为模拟量,因此EM235模块要实现D/A转换。一个EM235模块可同时扩展3路模拟量输入通道(接1路压力信号,2路振动信号)和1路模拟量输出通道(接至变频器)。
(2)起动
M1和M2各有两种起动方式,可通过转换开关选择变频/工频起动方式。
(3)运行
正常情况下,电动机M1处于变频调速状态,电动机M2处于停机备用状态。现场压力变送器检测管网出口压力(4~20mA模拟量信号),并与预定值相比较,经PLC内部专用PID指令进行运算,得到变频器所需频率信号,自动调节电动机转速,达到所需管网压力。
(4)停止
按下“停止按钮”,PLC控制所有接触器断开,变频器停止工作。
(5)切换
当需从电动机M1切换到M2时,接触器KM2断开,KM1闭合,此时电动机M1工作在工频下,在变频器完全停止后,KM4闭合,变频器重新起动,电动机M2在变频器驱动下起动;完全起动后,KM1断开,电动机M1停止,切换操作结束。电动机M2切换到M1过程类似。
(6)报警及故障自诊断
通过PLC内部程序设定报警及联锁保护,一旦出现故障立即停止相应操作并报警。对于故障自诊断功能,考虑到成本问题,未设计上位机,只设置相应故障代码,通过4位数码管显示,使维修人员可根据故障信息方便查找到故障点。如:(a)压缩机油压低、水压低等故障信号,可由现场防爆电接点压力表测得,直接送至PLC,由PLC控制实现声光报警和延时停车;(b)增设现场振动传感器,并将信号送至PLC,对压缩机运行状况进行显示和诊断。
四 几点体会和设计中应注意的问题
(1)采用变频控制后,实现了压缩机的软起动,减小了起动电流对电网的冲击;节电效果明显,1年内可回收全部投资。
(2)采用PLC后,组成闭环自控系统,实现自动调节,运行更加稳定可靠。
(3)变频器、PLC、接触器等可安装在一台控制柜内,可就地或远控操作,方式简单灵活。
(4)系统可扩展性较好。若有多台压缩机在变频/工频供电方式下运行时,只需将增加信息或信号引至PLC,即可实现整个系统的自动控制;若生产需要,本系统也可方便接入DCS或上位机,建立人机界面的监控系统等。
(5)预测性维护检修可大大延长压缩机使用寿命,提高可靠性,减少停车损失,降低运行费用。
(6)PLC控制电动机在变频/工频供电方式下切换时,须保证各接触器闭合和断开顺序以及足够的延时,以防止电动机绕组产生的感应电动势加载到变频器的输出逆变桥上,造成损坏。 pulse signals. After forming the system, it is often found that the transmission between instruments and equipment interferes with each other, resulting in system instability and even misoperation In addition to the performance reasons of each instrument and equipment, such as anti electromagnetic interference, another very important reason is that all kinds of instruments and equipment need to be grounded according to requirements and purposes. For example, the casing needs to be grounded for safety; In order to make the circuit work normally, the system should have a common reference point; In order to suppress interference, add a shield, and the shield also needs to be grounded However, due to the potential difference between the reference points between the instrument and the equipment (that is, the common location of each equipment is different), the problems of "ground circulation" and "grounding loop" are formed. When the circulating current is large, there will be a high common mode noise voltage, which will be coupled to the signal line through distributed parameters or directly connected to the level signal line, which will produce great series mode interference and even damage the interface circuit and equipment. 2) Natural interference lightning is a major natural interference source. The interference generated by lightning can be transmitted thousands of kilometers away. The time domain waveform of lightning interference is a large spike pulse superimposed on the background of a channeling random pulse. Cosmic noise is produced by ionizing radiation and changes constantly throughout the day. Solar noise changes dramatically with solar activity. Natural noise will mainly cause interference to communication, while lightning energy spike pulse can cause damage to many