Abstract: The redundant architecture of the safety instrumented function(SIF) loop should meet the requirement of safety and spurious trip rate(STR). Combining the experience on safety integrity level(SIL) verification, an engineering analysis is conducted on the standards and various mandatory constraints that affect the design of SIF redundant architecture, as well as the factors that affect the design of SIF loop redundant architecture, such as safety failure factor(SFF), mean failure rate, spurious trip rate, common cause failure(CCF), proof test interval, instrument measuring and manufacturing principle, constraints of instrument failure mode on redundant architecture degradation. Suitable redundant architecture design philosophies have been provided. A suitable redundant architecture design should include all components in the SIF loop. More instruments do not mean better neither do less instruments. If the economical condition permits, rationality should be the result of balancing safety and low spurious trip rate.

Key words: safety instrumented function(SIF), redundant architecture, safety failure factor(SFF), mean failure rate, spurious trip rate(STR), common cause failure(CCF), proof test interval, instrument failure mode

摘要： 安全仪表功能(SIF)回路的冗余架构应满足安全和误停车率的要求。结合安全完整性等级(SIL)验证工作的经验，对影响SIF冗余架构设计的标准及各种规定的强制约束和影响SIF回路冗余架构设计的因素，如：安全失效因子、平均失效率及误停车率、共因失效及检验测试时间间隔、仪表测量及制造原理、仪表故障模式对架构降级的约束等，进行了工程分析，给出了合理的冗余架构设计原则。合理的冗余架构设计，应当兼顾SIF回路中的各个部件，并非冗余仪表越多越好，也并非越少越好，在经济条件允许的前提下，合理性是在满足安全及减少误停车率之间平衡的结果。

关键词: 安全仪表功能, 冗余架构, 安全失效因子, 平均失效率, 误停车率, 共因失效, 检验测试时间间隔, 仪表故障模式