安全完善度等级SIL的概念与划分原则研究

安全完善度等级(Safety Integrity Level,SIL)是标识安全相关系统安全性要求的重要概念,它主要是根据系统安全功能一旦失效可能造成后果的严重程度及事故的发生频率进行划分.在轨道交通安全相关产品的设计开发过程中,需要根据SIL的高低确定设计开发团队的组成和所采用的设计方法,系统的安全防护措施等.目前,我国轨道交通行业在应用SIL概念时,存在一些误区,比如认为SIL越高越好,把某个产品或是系统描述为可以达到某个SIL等级要求.本文基于国际轨道交通安全标准对于SIL的定义,澄清了一些错误使用SIL的概念,总结了安全完善度等级的划分原则和方法,方法包括定量和定性两种,并通过实例加以说明.

Research on concept and allocation principle of safety integrity level

The Safety Integrity Level(SIL) is an important concept for safety related system to identify safety requirements.It is classified by the severity and frequency of the accidents caused by the failure of safety system.When designing and developing rail traffic safety related products,it is necessary to determine the developing team,their design methods and safety measures according to the level of SIL.Currently,there is some misunderstanding of the application of SIL concept in domestic rail transit industry.For example,some believe that the higher the level of SIL the better the product will be,and some describe a product or system as meeting the requirements of certain SIL.This paper describes the definition of SIL using international rail transit standard.It clarifies some incorrect use of the concept of SIL and introduces the definition,classification and determination methods of SIL,which includs quantitative and qualitative methods.Finally the paper illustrates these methods through application cases.