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The benefits of simplicity
•
A fundamental principle of IEC61511 is the limiting of size and complexity
in safety systems
•
Small, manageable safety systems designed to IEC61511 are often
made larger and more complex through the addition of asset/financial
protection functions
•
Clearly separate “convenience shutdown” actions from primary safety
function
•
Segregate highest SIL, or safety SILs in a dedicated logic solver and
lock-down after validation (taking signatures)
Neil Wakeling, August 2014