功能安全儀表對工業生產的安全運行至關重要，根據功能安全相關標準，設計了1001D結構的功能安全浮筒液位變送器。對其硬件電路進行FMEDA分析，得到各模塊失效率及安全失效分數SFF，并針對不同的故障模式設計相應的診斷方法，提高了變送器的診斷覆蓋率。通過建立馬爾可夫模型，對變送器的可靠性進行評估。結果表明，液位變送器安全完整性等級為SIL2，滿足功能安全儀表對相關指標的可靠性要求。

 

Reliability Design and Assess of Functional Safety Float Liquid Level Transmitter
 
MA Ben1, SUN Zi-qiang1, LI Qian-ru2
 
1. Key Laboratory of advanced chemical process control and optimization technology of Ministry of Education, East China University of Science and Technology, Shanghai, 200237
 
2. Shanghai automation instrument co., LTD, Shanghai, 200072
 
Abstract ： Functional safety instrument is very important to the operation safety of industrial production ， according to the functional safetyrelated standards, a functional safety float liquid level transmitter with 1oo1D architecture is designed. The failure rate and SFF of each module are obtained by adopting FMEDA for hardware circuits, and for different failure mode, it designs corresponding diagnosis methods to improve diagnostic coverage of the transmitter. The Markov model was established to access the reliability of transmitter. The results show that the Safety Integrity Level of liquid level transmitter is SIL2, meets the reliability requirements of relevant indicators of functional safety instrument.
 
Keywords：Functional Safety Instrument; Liquid Level Transmitter; FMEDA; Markov model; Safety Integrity Level