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Handout 4
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InstMC Functional Safety 2016Conference
Terminology .. Systematic Failure
3.6.6 Systematic failure
Failure, related in a deterministic way to a certain cause, which can only be
eliminated by a modification of the specification, design, manufacturing
process, operational procedures, documentation or other relevant factors.
IEC61508-4:2010
•
Resultant system failure rates can’t be accurately quantified because the
events that lead to them can’t be predicted
Restricted© SiemensAG 2013 All rights reserved.
Page 9
InstMC Functional Safety 2016Conference
Examples of types of Failures that can adversely affect a SIS
Failures
Random
hardware
failures
Fatigue
Ageing
Systematic
Failures
Human Error
Design
failure
Specification
failure
Interaction
error i.e.
Calibration
wrong
Environment
Excessive
Vibration
Over
Temperature
Other
Software
bugs
Data Comms
errors
Predictable,
Quantifiable
Unpredictable, Unquantifiable
Persistent or Intermittent