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 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 More31-Dec-2011 – Are YOU ready?
31-December-2011 marks a key milestone for machine builders marketing their products in the European Union, the EEA and many of the Candidate States. Functional Safety takes a positive step forward with the mandatory application of EN ISO 13849 – 1 and ‑2. As of 1‑January-2012, the safety-related parts of the control systems on all machinery bearing a CE Mark will be…
Read MoreInterlock Architectures Pt. 6 – Comparing North American and International Systems
I’ve now written six posts, including this one, on the topic of circuit architectures for the safety-related parts of control systems. In this post, we’ll compare the International and North American systems. This comparison is not intended to draw conclusions about which is “better”, but rather to compare and contrast the two systems so that…
Read MoreInterlock Architectures – Pt. 5: Category 4 — Control Reliable
Ed. note: I’ve made a few updates to this article since it was first published in 2011, with the most recent today, 6‑Dec-18. – DN – The most reliable of the five system architectures, Category 4 is the only architecture that uses multiple-fault tolerant techniques to help ensure that component failures do not result in an unacceptable…
Read MoreInterlock Architectures – Pt. 4: Category 3 – Control Reliable
This post was updated on 2020-03-28. Category 3 system architecture is the first category that could be considered to have similarity to “Control Reliable” circuits or systems as was defined in some North American standards, now obsolete (notably CSA Z432-04, CSA Z434-03, and ANSI/RIA R15.06 – 1999). ISO 13849 – 1 Category 3 is NOT the same as Control Reliable, but we’ll…
Read MoreUnderstanding Risk Assessment
When people discuss ‘Risk’ there are a lot of different assumptions made about what that means. For me, the study of risk and risk assessment techniques started in 1995. As a technologist and controls designer, I had to somehow wrap my head around the whole concept in ways I’d never considered. If you’re trying to figure out risk…
IEC/TR 62061 – 1 Reviewed
Why You Need to Spend More Cash on Yet Another Document Standards organizations publish documents in a fairly continuous stream, so for those of us tasked with staying current with a large number of standards (say, more than 10), the publication of another new standard or Technical Report isn’t news – it’s business as usual. The question…
Read MoreInterlock Architectures – Pt. 3: Category 2
This article explores the requirements for safety related control systems meeting ISO 13849 – 1 Category 2 requirements. “Gotcha!” points in the definition are highlighted to help designers avoid this common pitfalls.
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