I am afraid I have little time today to enter this interesting debate in depth, but I feel that a couple of quick points are worth making:
- While EN ISO 13849-1 has replaced EN 954-1 so far as the standards bodies are concerned, there are many people in industry who continue to use EN 954-1 and it remains on the list of standards which provide a presumption of conformity with the Machinery Directive until at least the end of next year. - EN ISO 13849 is a controversial standard and has some significant failings in real world applications, not least of which is its reliance on a mathematical approach which is simply incomprehensible to many users. Having said this, the standard is probably a necessary step in the development of a more coherent approach to (particularly) safety systems which rely on complex electronics. It is already under review and, if nothing else, is likely to be updated to make its terminology more consistent with other standards derived >from IEC 61508. The timetable for this is, I understand, a couple of years or so. The question as to why various industry sectors are not getting more consistent is important, and I think that it's true to say that in fact they are, although it is a very slow process. However, it's also important to recognise that there is no 'one size fits all' approach to this problem, and the reason that there are so many different standards is because the approaches need to be different in different applications. For example, in the machine control field, where an operator may set a control and then leave the machine to get on with its work without supervision, the control system needs to behave in a very different way to that in an automobile where there is an operator in constant attendance, and who usually has a variety of measures which they can apply to avoid a particular hazard. Nick. At 15:48 -0800 1/11/10, Brian O'Connell wrote: >EN954-1 was replaced by EN13849-1 in 2007. The latter appeals to me >as a math weenie (it uses a probabilistic approach), but it concerns >me that the math is supposed to be a fix to avoid 'systematic' >failures. I do not have any relevant experience with the safety of >machinery, so I would appreciate others' comments. > >Functional Safety, HBSE, Risk Mitigation - they overlap; they are >not the same. And I want to know why various industry sectors are >not getting more consistent. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
