Doug Nix will be giving the third session in the three-part Introduction to Functional Safety seminar series at the IEEE Product Safety Engineering Society Virtual Chapter meeting.’ In this third of three sessions, Doug will be introducing key functional safety concepts MTTFD, DCavg, and CCF, and will be discussing Safety-related Software Development and Verification and…
Read MoreQ & A: Category 2 and Testing Intervals
During the Free Safety Talks that we did with Schmersal Canada and Franklin Empire, we had a “hot question” come up regarding Category 2 architecture and the testing interval requirement. The definition of Category 2 in 6.2.5 does not include any mention of a minimum testing rate, but 4.5.4 “Simplified procedure for estimating the quantifiable aspects of PL”…
Read MoreFive reasons you should attend our Free Safety Talks
Reason #1 – Free Safety Talks You can’t argue with Free Stuff! Last week we partnered with Schmersal Canada and Franklin Empire to put on three days of Free Safety Talks. We had full houses in all three locations, Windsor, London and Cambridge, with nearly 60 people participating. We had two great presenters who helped…
Read MoreSafe Drive Control including Safe Torque Off (STO)
Ed. Note: This article was revised 25-Jul-17 to include information on safe standstill. Safe Drive Control including STO Motor drives are everywhere. From DC variable speed drives and indexing drives, through AC Variable Frequency drives, servo drives and stepper motor drives, the capabilities and the flexibility of these electronic systems has given machine designers unprecedented…
Read MoreHow to do a 13849 – 1 analysis: Complete Reference List
Post updated 2019-07-24. Ed. As promised in previous posts, here is the complete reference list for the series “How to do a 13849 – 1 analysis”! If you have any additional resources you think readers would find helpful, please add them in the comments. Copyright secured by Digiprove © 2017 – 2018Acknowledgements: As cited.Some Rights ReservedOriginal content here is published under these license terms: X License Type:Non-commercial, Attribution,…
ISO 13849 – 1 Analysis — Part 8: Fault Exclusion
Post updated 2019-07-24. Ed. Fault Consideration & Fault Exclusion ISO 13849 – 1, Chapter 7 [1, 7] discusses the need for fault consideration and fault exclusion. Fault consideration is the process of examining the components and sub-systems used in the safety-related part of the control system (SRP/CS) and making a list of all the faults that could occur in each…
ISO 13849 – 1 Analysis — Part 7: Safety-Related Software
Post updated 2019-07-24. Ed. Safety-Related Software Up to this point, I have been discussing the basic processes used for the design of safety-related parts of control systems. The underlying assumption is that these techniques apply to the design of hardware used for safety purposes. The remaining question focuses on the design and development of safety-related software…
Read MoreISO 13849 – 1 Analysis — Part 6: CCF — Common Cause Failures
Post updated 2019-07-24. Ed. What is a “Common Cause Failure”? There are two similar-sounding terms that people often get confused: Common Cause Failure (CCF) and Common Mode Failure. While these two types of failures sound similar, they are different. A Common Cause Failure is a failure in a system where two or more portions of the system fail at…
Read MoreISO 13849 – 1 Analysis — Part 5: Diagnostic Coverage (DC)
Post updated 2019-07-24. Ed. What is Diagnostic Coverage? Understanding Diagnostic Coverage (DC) as it is used in ISO 13849 – 1 [1] is critical to analysing the design of any safety function assessed using this standard. In case you missed a previous part of the series, you can read it here. In the last instalment of this series discussing…
Read MoreISO 13849 – 1 Analysis — Part 4: MTTFD – Mean Time to Dangerous Failure
Post updated 2019-07-24. Ed. Functional safety is all about the likelihood of a safety system failing to operate when you need it. Understanding Mean Time to Dangerous Failure, or MTTFD, is critical. If you have been reading about this topic at all, you may notice that I am abbreviating Mean Time to Dangerous Failure with all capital…
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