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. Book List Here are some books that I think you may find helpful on this journey: [0] […]
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 one. This a definitely non-trivial […]
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 the same time from a single […]
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 […]
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 […]
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 […]
Category 3 system architecture is the first category that could be considered to have similarity to “Control Reliable” circuits or systems as defined in the North American standards. It is not the same as Control Reliable, but we’ll get to in a subsequent post. If you haven’t read the first three posts in this series, you may […]
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 […]
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 […]
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.