分散控制系统开关量输出接口问题及其解决方法

Interface problem of on-off output in distributed control system and its solution

广州珠江发电厂分散控制系统项目的实施过程中,与开关量输出卡连接的小型继电器出现了触点非正常抖动的问题,其原因是开关量输出卡两端并联的阻容回路对串接的继电器线圈形成电回路,激励线圈,导致其触点发出误动作信号。为此,提出了在继电器两端并联一个电阻器或者电容器的改进方案,使其起到降低输出继电器两端激励电压的作用。经计算分析,选择了并接电容器的方案。实践证明,该方案是切实可行的,消除了事故隐患。

In the implementation of DCS (distributed control system) project in Guangzhou Zhujiang Power Plant,abnormal contact chattering emerged on the small relay connected with onoff output card.The RC loop parallel with the card formed an electric circuit on the series relay coil to excite the coil and make the contact maloperate.Therefor,it is suggested that a resistor or a capacitor be connected with the relay in parallel to lower the exciting voltage at both ends of the output relay.Based on calculation and analysis,the shunt capacitor plan is selected and satisfactory results obtained.