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© ABB
| Slide 35
Why Do We Test?
to expose un-revealed failures
Test
Test
Test
Demand
Test
Test
Test
Interval
Dead
Time
Test
Unrevealed
fault
Time (years)
Healthy
Faulty
SIF
Hazardous
Event
Plant in
Safe State
How often should you test?
IEC61511-1 clause 16.3.1.3 states ‘The proof test interval shall be as decided
using the PFDavg calculation.’
Nov 04, 2014