Frequently Asked Question
If the Partial Stroke test is done in "Manual" mode, the architectural constraint limits the SIL level to "1", whereas - If the Partial Stroke test is done in "Automatic" mode, the architectural constraint meets the SIL level "2" requirement. Could you pl
Last Updated a year ago
IEC 61508/61511 require that a diagnostic is implemented automatically for it to be considered a detected failure. What this means is that if the PVST is done automatically, the SFF calculation will take into consider the partial stroke diagnostics. Whereas, if the test is initiated manually, the PVST coverage is not. Typically, this means you will not have a SFF high enough to meet SIL 2 in the manual initiation scenario.