Ultima modifica: 20/06/2023
Chapter 7 deals with the four Architectures of IEC 62061. IEC 62061 remains linked to IEC 61508 approach of Route 1H.
In low demand mode, components are classified as Type A or Type B and there are two different tables to be used to decide what is the maximum SIL that a Safety Subsystem can reach. In IEC 62061, one table only is defined for all types of components and its content is similar to the one used for Type B components.
In the context of hardware safety integrity, the highest level that can be claimed by a safety-related control Systems or SCS is limited by the hardware fault tolerances (HFT) and safe failure fractions (SFF) of the subsystem that carries out the safety function: the reference to be used is Table 6 shown hereafter.
Qui i paragrafi del libro:
– Failure Rate (λ)
– Safe Failure Fraction (SFF)
– Diagnostic Coverage (DC)
– Safety Integrity and Architectural Constraints
– Mean Time to Failure (MTTF)
– Common Cause Failure (CCF)
– Proof Test
– Mission Time and Useful Lifetime