关于DCS和SIS共用传感器的若干问题

Some Issues About Sharing Sensors Between DCS and SIS

针对构建安全仪表系统(SIS)和分散控制系统(DCS)各自独立保护层(IPL)时,不建议SIS和DCS共用传感器问题,分析了DCS独立保护层的数量问题,提出了LOPA的保护层设计改进方案:由SIL2的1个SIS独立保护层,取代DCS和SIS(SIL1)2个保护层,并从要求时危险失效平均概率结构约束和系统完整性三个方面,进行了SIL等级验证。该方案证明了带SIL2认证的传感器和信号分配器可不做冗余,直接构建SIL2的回路。验证结论表明,在一定前提条件下,SIS和DCS可以共用传感器,而不必独立设置。

Generally it is not recommended that safety instrumented system(SIS)and.distributed control system(DCS)share sensors when building their respective independent protection layers(IPL).The number of independent protection layers of DCS is analyzed,an improved scheme of LOPA is proposed:using a SIL2 protection layer replaces the two protection layers of DCS and SIS(SIL1),and SIL level verification is carried out from the three aspects of PFD_(avg) calculation,structural constraints and system integrity.The scheme is proved that the sensor and signal distributor with SIL2 certification can directly construct the SIL2 loop without redundancy.The verification results show that under certain conditions,SIS and DCS can share sensors without setting them independently.