为探究如何更加实际的评价全自动运行(FAO)系统核心子系统功能的安全完整性等级(SIL),通过研究欧洲电工标准化委员会(CENELEC)标准中风险模型的构造,给出了风险降低因素(RRF)的定义；通过定义的RRF,建立了可容忍事故率(TAR)与可容忍危害率(THR)的换算关系,进而评估出FAO系统核心子系统功能次级危害的THR；最后再通过THR与SIL的对应关系,得到了核心子系统功能的SIL。应用结果：结合实际的FAO工程项目应用成果,给出了RRF中各要素的具体示例,可供借鉴；与直接采用TAR保守估计SIL的方法相比,在考虑RRF后评估得到的SIL更接近实际情况。

In order to explore how to evaluate the functions safety integrity level (SIL) of the core subsystem of the fully automatic operation (FAO) system more practically, by studying the structure of the risk model in the European Committee for Electrotechnical Standardization (CENELEC) standard, the definition of risk reduction factor (RRF) is given. Through the defined RRF, the conversion relationship between the tolerable accident rate (TAR) and the tolerable hazard rate (THR) is established, and then the THR of the secondary hazards of the core subsystem functions of the FAO system is evaluated. Through the corresponding relationship between THR and SIL, the functions SIL of the core subsystem is obtained. Application results: Combined with the actual application results of FAO engineering project, specific examples of each element in RRF are given for reference. Compared with the method of conservatively estimating SIL by directly using TAR, the SIL estimated after considering RRF is closer to reality condition.

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