In EN 62061, the maximum achievable SIL is determined via the dependency between the hardware fault tolerance and the safe failure fraction (SFF). The SFF is calculated by assessing all possible types of component failures and establishing whether each of these failures results in a safe or unsafe condition. The result provides the system's SFF.
The structural analysis also indicates whether there is any fault tolerance. If the fault tolerance is N, the occurrence of N+1 faults can lead to the loss of the safety function. The following table shows the maximum potential SIL, based on the fault tolerance and SFF. 
No comments:
Post a Comment