CyberCertPrepOT Security FundamentalsOT Fundamentals: Safety Systems & Physical SecurityHARDFree question
A function verifies at an average PFD of 0.0005 in low demand mode. Which SIL does IEC 61508 assign and what is the matching reduction factor?
- A.SIL 4 with a reduction factor of 20000
- B.SIL 3 with a reduction factor of 2000
- C.SIL 2 with a reduction factor of 200
- D.SIL 3 reached through a factor of 5000
Why B is correct
0.0005 is inside the SIL 3 band of 0.0001 to 0.001 and the reduction factor is 1 / 0.0005 = 2000. The other choices either pick the wrong band or invert the figure incorrectly.
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