Advertisement

Probability of Failure on Demand – The Why and the How

  • Jens Braband
  • Rüdiger vom Hövel
  • Hendrik Schäbe
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5775)

Abstract

In the paper, we will study the PFD and its connection with the probability of failure per hour and failure rates of equipment using very simple models. We describe the philosophies that are standing behind the PFD and the THR. A comparison shows, how the philosophies are connected and which connections between PFH and PFD are implied. Depending on additional parameters, there can be deviations between safety integrity levels that are derived on the basis of the PFD and the PFH. Problems are discussed, which can arise when working with the PFD. We describe, how PFD and PFH in IEC 61508 are connected with the THR defined in the standard EN 50129.

We discuss arguments that show, why care is needed when using the PFD. Moreover, we present a reasoning, why a probability of failure on demand (PFD) might be misleading.

Keywords

Probability of failure on demand rate of dangerous failures safety integrity level 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    IEC 61508-1 Functional safety of electrical / electronic / programmable electronic safety-related systems – Part 1: General requirements, 1st edn. (1998)Google Scholar
  2. 2.
    IEC 61508-1 Functional safety of electrical / electronic / programmable electronic safety-related systems, Part 1: General requirements, Committee Draft For Vote (CDV) (2008) Google Scholar
  3. 3.
    EN 50129 Railway applications – Communication, signalling and processing systems –Safety-related electronic systems for signalling (2003)Google Scholar
  4. 4.
    JAR 25 Large Aeroplanes Google Scholar
  5. 5.
    Kafka, P.: How safe is safe enough? – An unresolved issue for all technologies, Safety and Reliability. In: Schueller, G.I., Kafka, P. (eds.), vol. 1, pp. 385–390. Balkema, Rotterdam (1999)Google Scholar
  6. 6.
    Kuhlmann, A.: Introduction to Safety Science. Springer, New York (1986)CrossRefGoogle Scholar
  7. 7.
    Saint-Onge, D.: Environmental Cleanup: What is Acceptable Risk, TriMediaConsultants, www.trimediaconsultants.com/risk.pdf
  8. 8.
    Skjong, R., Eknes, M.: Economic activity and societal risk acceptance. In: Zio, E., Demichela, M., Piccinini, N. (eds.) ESREL 2001 Towards a safer world, vol. 1, pp. 109–116. Politecnico die Torino, Torino (2001)Google Scholar
  9. 9.
    Schäbe, H.: Different Approaches for Determination of Tolerable Hazard Rates. In: Zio, E., Demichela, M., Piccinini, N. (eds.) ESREL 2001 Towards a safer world, vol. 1, pp. 435–442. Politecnico die Torino, Torino (2001)Google Scholar
  10. 10.
    Schäbe, H.: The Safety Philosophy behind the CENELEC Railway Standards. In: Decision Making and risk management, Proceedings of the conference ESREL 2002, Lyon, March 19 – 21, pp. 788–790 (2002)Google Scholar
  11. 11.
    Schäbe, H.: Apportionment of safety integrity levels in complex electronically controlled systems. In: Bedford, T., van Gelder, P.H.A.J.M. (eds.) Safety & Reliability – ESREL 2003, vol. 2, pp. 1395–1400. Balkema, Lisse (2003)Google Scholar
  12. 12.
    Schäbe, H., Wigger, P.: Experience with SIL Allocation in Railway Applications. In: Proceedings of the 4th International Symposium ”Programmable Electronic Systems in Safety Related Applications”, TÜV, Cologne, May 3 – 4 (2000)Google Scholar
  13. 13.
    Vatn, J.A.: Discussion of the Acceptable Risk Problem. Reliability Engineering and System Safety 61, 11–19 (1998)CrossRefGoogle Scholar
  14. 14.
    Braband, J.: Risikoanalysen in der Eisenbahn-Automatisierung. Eurailpress (2005)Google Scholar
  15. 15.
    Braband, J.: Ein Ansatz zur Vereinheitlichung der Betriebsarten und Sicherheitsziele nach IEC 61508. In: Schnieder, E. (ed.) Entwurf komplexer Automatisierungssysteme, Proceedings EKA 2006, Brunswick, pp. 153–160 (2006)Google Scholar
  16. 16.
    Braband, J.: Safety Analysis based on IEC 61508: Lessons Learned and the Way Forward, Invited Talk. In: SAFECOMP 2006, Gdansk (2006)Google Scholar
  17. 17.
    Birolini, S.: Reliability Engineering. Springer, Berlin (2007)zbMATHGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Jens Braband
    • 1
  • Rüdiger vom Hövel
    • 2
  • Hendrik Schäbe
    • 2
  1. 1.Siemens AG, Industry Sector, Mobility Division, Rail Automation, Research & DevelopmentBrunswickGermany
  2. 2.TÜV Rheinland InterTraffic GmbH, Assessment & Certification Rail, Am Grauen SteinCologneGermany

Personalised recommendations