Module 12 - SIF Design and SIL verification

Question 1

What are the two methods IEC 61511 and 61508 propose for determining the minimum SIL under architectural constraints?

Answer 1

1. IEC 61511 ED. 2 Table 6

2. IEC 61508-2 Route 1H

Question 2

What is a type A device vs a Type B device? What does this impact?

Answer 2

1. Type A = Simple
2. Type B = Complex

Impacts which table to use in 61508

Question 3

How do you calculate PFDavg for an entire SIF?

Answer 3

Sum the component elements individual PFD values

Question 4

Have you reviewed the calculation case study?

Answer 4

I hope so

Question 5

What are the three overall steps to follow in achieving a SIL rating?

Answer 5

1. Satisy HFT
2. Satisfy PFD
3. Satisfy SC

Question 6

Using a certificate, how can you find Ldu for a logic solver?

Answer 6

For a logic solver, MTTF is actually MTTFdu, where Ldu is the inverse of MTTF