A Devil’s Advocate on SIL 4

  • Odd Nordland
Conference paper


The concept of safety integrity levels is well established and for many safety critical systems SIL 4 is demanded by default. The problem with SIL 4 is that it is impossible to prove and the demand is often not justified. A devil’s advocate view is adopted and a number of questions related to demanding SIL 4 are asked and the problems to be addressed when answering them are discussed


Hazard Rate Fault Tree Tolerable Region Fault Tree Analysis Safety Critical System 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. CENELEC (2003) Railway applications - Communication, signalling and processing systems Safety related electronic systems for signalling. EN 50129. CENELEC, Brussels, BelgiumGoogle Scholar
  2. IEC (1998) Functional safety of electrical/electronic/programmable electronic safety-related systems. IEC 61508. International Electrotechnical Commission, Geneva, SwitzerlandGoogle Scholar

Copyright information

© Springer-Verlag London Limited 2012

Authors and Affiliations

  • Odd Nordland
    • 1
  1. 1.SINTEF ICTTrondheimNorway

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