[PSES] definitions of safety-related words and phrases
“…terminology like Basic Safeguard Parameters and Supplementary Safeguard Parameters used in Figure 45 do not seem to be defined anywhere.” I invite readers of this list to provide definitions of the words: basic: supplementary: safeguard: parameter: Once these are defined, provide definitions of the phrases: basic safeguard parameter: supplementary safeguard parameter: No right or wrong. These terms are used in 62368-1 and 62368-2, but seem not defined or not well-defined. I am trying to determine whether the words and phrases have a common meaning among standards users and product safety practitioners. Maybe the standards need a better and more complete set of defined terms. Thanks, Rich - 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 EMC-PSTC@LISTSERV.IEEE.ORG All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/emc-pstc@listserv.ieee.org/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: msherma...@comcast.net Rick Linford at: linf...@ieee.org For policy questions, send mail to: Jim Bacher: _ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
Re: [PSES] Consistency of safety definitions
And I would also like to know that as well. :-) John Sent from my Fonepad "Nyffenegger, Dave" wrote:>So does the "Same situation is present also in other bodies in which are preferred committee-administrators rather than technologically-experienced engineering professionals” apply to IEEE as well? > >-Dave > >-Original Message- >From: John Woodgate [mailto:j...@jmwa.demon.co.uk] >Sent: Saturday, January 17, 2015 8:40 AM >To: EMC-PSTC@LISTSERV.IEEE.ORG >Subject: Re: [PSES] Consistency of safety definitions > >In message <07fd01d03250$268b24d0$73a16e70$@post.tau.ac.il>, dated Sat, >17 Jan 2015, Steli Loznen writes: > >>Indeed, except few TCs, the IEC “really only looking for >>committee-administrators rather than technologically-experienced >>engineering types”. > >JMW: John Allen applied that to BSI, not IEC, and it's not true of the IEC CO Engineers, nor TC/SC chairs and secretaries. > >This, also, was not about IEC: > >Same situation is present also in other bodies in which are preferred “committee-administrators rather than technologically-experienced engineering professionals”. > >JMW: However, the IEC Central Office editors are mostly language experts but that doesn't extend to some engineering terms, such as '10 metres square'. > >ACOS is the Advisory Committee on Safety and reports to the Standards management Board (SMB). It doesn't deal with terminology in general. You are really asking for at least an 'ACOT' - Advisory Committee on Terminology' or maybe a more powerful body than TC1, which is at present responsible for terminology. > >You also say: > > The reason can be found in the lack of interest of the young generation to be involved in a “pro buono” voluntary activity > >JMW: [It's 'bono', not buono.] > >The IEC Young Professionals scheme is actively recruiting younger people to standards work. > >and only the big companies and laboratories are ready to support financially the standard development activities. > >JMW: It's not a question of 'willing', smaller companies still see standards work as an expense, and not a negligible one. But they need to be shown the countervailing *advantages* of participation. Some effort is put into this, but nowhere near enough. > >We are close to a critical situation, when only the “interested” >bodies will impose them point of view and the procedure for “consensus voting” by the P-members will become, regrettably, formal an strong influenced by these “interested” global organizations. > >Smaller companies can share participation costs through trade associations. There is *always* a way. There is no ground for claiming exclusion. >-- >OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK > >- > >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 > >All emc-pstc postings are archived and searchable on the web at: >http://www.ieee-pses.org/emc-pstc.html > >Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. > >Website: http://www.ieee-pses.org/ >Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html > >For help, send mail to the list administrators: >Scott Douglas >Mike Cantwell > >For policy questions, send mail to: >Jim Bacher: >David Heald: > >- > >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 > >All emc-pstc postings are archived and searchable on the web at: >http://www.ieee-pses.org/emc-pstc.html > >Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. > >Website: http://www.ieee-pses.org/ >Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) >List rules: http://www.ieee-pses.org/listrules.html > >For help, send mail to the list administrators: >Scott Douglas >Mike Cantwell > >For policy questions, send mail to: >Jim Bacher: >David Heald: - This message is from the IEEE Product Safety Engineering
Re: [PSES] Consistency of safety definitions
So does the "Same situation is present also in other bodies in which are preferred committee-administrators rather than technologically-experienced engineering professionals” apply to IEEE as well? -Dave -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Saturday, January 17, 2015 8:40 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Consistency of safety definitions In message <07fd01d03250$268b24d0$73a16e70$@post.tau.ac.il>, dated Sat, 17 Jan 2015, Steli Loznen writes: >Indeed, except few TCs, the IEC “really only looking for >committee-administrators rather than technologically-experienced >engineering types”. JMW: John Allen applied that to BSI, not IEC, and it's not true of the IEC CO Engineers, nor TC/SC chairs and secretaries. This, also, was not about IEC: Same situation is present also in other bodies in which are preferred “committee-administrators rather than technologically-experienced engineering professionals”. JMW: However, the IEC Central Office editors are mostly language experts but that doesn't extend to some engineering terms, such as '10 metres square'. ACOS is the Advisory Committee on Safety and reports to the Standards management Board (SMB). It doesn't deal with terminology in general. You are really asking for at least an 'ACOT' - Advisory Committee on Terminology' or maybe a more powerful body than TC1, which is at present responsible for terminology. You also say: The reason can be found in the lack of interest of the young generation to be involved in a “pro buono” voluntary activity JMW: [It's 'bono', not buono.] The IEC Young Professionals scheme is actively recruiting younger people to standards work. and only the big companies and laboratories are ready to support financially the standard development activities. JMW: It's not a question of 'willing', smaller companies still see standards work as an expense, and not a negligible one. But they need to be shown the countervailing *advantages* of participation. Some effort is put into this, but nowhere near enough. We are close to a critical situation, when only the “interested” bodies will impose them point of view and the procedure for “consensus voting” by the P-members will become, regrettably, formal an strong influenced by these “interested” global organizations. Smaller companies can share participation costs through trade associations. There is *always* a way. There is no ground for claiming exclusion. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Consistency of safety definitions
In message ITMZdEBAA==@blueyonder.co.uk>, dated Sat, 17 Jan 2015, John Allen writes: OK then, so you are talking (at least in part) about an "ACOT" and not the "ACOS" - so how could the creation of that be achieved? (I ask this because, like many others on the forum, I am not familiar with the intricacies of the structures and operation of the current IEC operations). For you and others in UK, write to the Secretary of the British Electrotechnical Committee at BSI Chiswick. Don't mention my name or he will extract a dire penalty.(;-) And, with regard to your other post, with respect to the participation of smaller companies in national and internationals standards-making committees, it is not a matter of them (and I have worked in an awful lot!) not considering such activities to be important but the plain fact is that (and especially in the recent and current economic climate) they just cannot spare important members of their staffs to do it because they are working flat-out just to get their products to market within very tight time/cost scales. I fully realise the difficulty but it's a matter of setting priorities. If you want to influence standards, you *have* to devote time to it. Oh, & BTW, as I am sure you well know, the routes/costs/ timescales in getting involved in trade-bodies and the like, which contribute to national standards-preparation activities, would further add to those burdens and barriers, and so is even more like to stop them even trying to participate. Again, you have a choice: you can't get the influence without devoting resources. No-one said it was easy, but few things are. Finally, and again with regard to the smaller companies, their staff are usually focused on only one or two specific standards, and most of them do not have the breadth of experience to appreciate the differences between those and the "parallel" standards for other types of products, and the effects that those differences can have on the overall compliance processes. There are ways round that, but of course more time is required; not necessarily a lot, but some. That is why it seems important to me (us?) that the older and more experienced people, who have both the interest and the time to get involved in forward-looking activities like we discussing, should encouraged to do so, and with the very broad but definite objectives that we are discussing in mind. I entirely agree; that's why I'm still doing a lot of standards work at the age of 77. But we MUST have much younger people as well as us dinosaurs. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Consistency of safety definitions
John OK then, so you are talking (at least in part) about an "ACOT" and not the "ACOS" - so how could the creation of that be achieved? (I ask this because, like many others on the forum, I am not familiar with the intricacies of the structures and operation of the current IEC operations). And, with regard to your other post, with respect to the participation of smaller companies in national and internationals standards-making committees, it is not a matter of them (and I have worked in an awful lot!) not considering such activities to be important but the plain fact is that (and especially in the recent and current economic climate) they just cannot spare important members of their staffs to do it because they are working flat-out just to get their products to market within very tight time/cost scales. Oh, & BTW, as I am sure you well know, the routes/costs/ timescales in getting involved in trade-bodies and the like, which contribute to national standards-preparation activities, would further add to those burdens and barriers, and so is even more like to stop them even trying to participate. Finally, and again with regard to the smaller companies, their staff are usually focused on only one or two specific standards, and most of them do not have the breadth of experience to appreciate the differences between those and the "parallel" standards for other types of products, and the effects that those differences can have on the overall compliance processes. That is why it seems important to me (us?) that the older and more experienced people, who have both the interest and the time to get involved in forward-looking activities like we discussing, should encouraged to do so, and with the very broad but definite objectives that we are discussing in mind. Regards John -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 17 January 2015 13:41 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Consistency of safety definitions In message <001701d03256$2440ff00$6cc2fd00$@blueyonder.co.uk>, dated Sat, 17 Jan 2015, John Allen writes: >You have made some very good points, and particularly that about an >Action Group to approach ACOS – I suppose that the next question on >that would about setting up such a group and what its approach should be? This is outside the scope of ACOS - see my other current post. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Consistency of safety definitions
In message <001701d03256$2440ff00$6cc2fd00$@blueyonder.co.uk>, dated Sat, 17 Jan 2015, John Allen writes: You have made some very good points, and particularly that about an Action Group to approach ACOS – I suppose that the next question on that would about setting up such a group and what its approach should be? This is outside the scope of ACOS - see my other current post. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Consistency of safety definitions
In message <07fd01d03250$268b24d0$73a16e70$@post.tau.ac.il>, dated Sat, 17 Jan 2015, Steli Loznen writes: Indeed, except few TCs, the IEC “really only looking for committee-administrators rather than technologically-experienced engineering types”. JMW: John Allen applied that to BSI, not IEC, and it's not true of the IEC CO Engineers, nor TC/SC chairs and secretaries. This, also, was not about IEC: Same situation is present also in other bodies in which are preferred “committee-administrators rather than technologically-experienced engineering professionals”. JMW: However, the IEC Central Office editors are mostly language experts but that doesn't extend to some engineering terms, such as '10 metres square'. ACOS is the Advisory Committee on Safety and reports to the Standards management Board (SMB). It doesn't deal with terminology in general. You are really asking for at least an 'ACOT' - Advisory Committee on Terminology' or maybe a more powerful body than TC1, which is at present responsible for terminology. You also say: The reason can be found in the lack of interest of the young generation to be involved in a “pro buono” voluntary activity JMW: [It's 'bono', not buono.] The IEC Young Professionals scheme is actively recruiting younger people to standards work. and only the big companies and laboratories are ready to support financially the standard development activities. JMW: It's not a question of 'willing', smaller companies still see standards work as an expense, and not a negligible one. But they need to be shown the countervailing *advantages* of participation. Some effort is put into this, but nowhere near enough. We are close to a critical situation, when only the “interested” bodies will impose them point of view and the procedure for “consensus voting” by the P-members will become, regrettably, formal an strong influenced by these “interested” global organizations. Smaller companies can share participation costs through trade associations. There is *always* a way. There is no ground for claiming exclusion. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Consistency of safety definitions
Stelli You have made some very good points, and particularly that about an Action Group to approach ACOS – I suppose that the next question on that would about setting up such a group and what its approach should be? For starters, I think that there is a need for a list of the main areas of “non-harmonization” of requirements that are effectively the same in different standards but where different criteria (e.g. definitions, test methods, pass/fail criteria, marking & labelling, risk assessment processes, etc.) are applied by those standards, and where there is no obvious (or even subtle!) reason why they should actually be any different for technological reasons. The list should cover as many of the “main standards”, and should include those for components and sub-assemblies which have widespread application. For example, I’m working in the 61010 instrumentation field and the moment, and that makes a lot of use of connectors of various types – but very few of the component connector standards include the physical environment requirements which are similar to those given in 61010 (and often include a lot that are not, such as IEC 60068 and MIL-Spec tests), and so that causes extra assessment time, grief, cost and the occasional (or more often sometimes!) “guesstimate” or ad hoc test to confirm if a connector is actually suitable for the purpose for which we need it (and then we might have to justify the divergences from 61010 via the Cl 17 Risk Assessment approach)! Once a list begins to be compiled then the focus of an Action Group would become clearer, and it could then more easily decide what it should approach the ACOS with and how it should be done – get the ammunition and then decide where and how to fire the guns! I will assist if/where I can! Regards John From: Steli Loznen [mailto:rshap...@post.tau.ac.il] Sent: 17 January 2015 12:22 To: 'John Allen'; 'John Woodgate'; ri...@ieee.org Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] Consistency of safety definitions Dear John A., John W. and Rich; Dear all, As an active participant from 1994 in the standards development (IEC-TC62-SC62A) I strongly agree with the comments referring to the non-harmonization present on this activity. The issues raised by you, unfortunately represent the reality. Indeed, except few TCs, the IEC “really only looking for committee-administrators rather than technologically-experienced engineering types”. The reason can be found in the lack of interest of the young generation to be involved in a “pro buono” voluntary activity and only the big companies and laboratories are ready to support financially the standard development activities. We are close to a critical situation, when only the “interested” bodies will impose them point of view and the procedure for “consensus voting” by the P-members will become, regrettably, formal an strong influenced by these “interested” global organizations. Now shall be the time when ACOS need to play his coordinative professional role. An example refer to the inertia in adoption for Basic Safety tests a harmonized methodology applicable to all products categories. Which differences exist i.e for heating test or for leakage current measurement, between different products categories? Any difference. But each product standard present his own test method. Useless and confusing. Another example is, as was mentioned already in this discussion, the absence of a harmonized terminology and definition of terms. Same situation is present also in other bodies in which are preferred “committee-administrators rather than technologically-experienced engineering professionals”. Maybe we as professionals with wide and long experience in the field needs now to take a position and to ask IEC, ACOS to “open the eyes” until will be late. I am ready to participate in such Action Group for rescue the Products Safety Engineering from falling in a routine and a “dedicated” (“interested”) process. Maybe this alarm signal can help. Steli Steli Loznen, M.Sc., SM-I Member of IEEE-PSES BoD 17-3 Shaul HaMelech Blvd. 64367 Tel Aviv ISRAEL Tel:+972-3-6912668 Fax:+972-3-6913988 Mobile:+972-54-7245794 E-mail: <mailto:sloz...@ieee.org> sloz...@ieee.org From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: Saturday, January 17, 2015 10:29 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Consistency of safety definitions Rich, (and John, of course!) Thanks for the insight, but not for the “bad news”! Having been a little involved in standards-making in the (dim and distant, it has to be said – see below!), past, it’s got to be sad that those types of influences can prevail in the modern world, especially given the significant overall progress towards global harmonization of requirements. I think a significant part of
Re: [PSES] Consistency of safety definitions
Dear John A., John W. and Rich; Dear all, As an active participant from 1994 in the standards development (IEC-TC62-SC62A) I strongly agree with the comments referring to the non-harmonization present on this activity. The issues raised by you, unfortunately represent the reality. Indeed, except few TCs, the IEC “really only looking for committee-administrators rather than technologically-experienced engineering types”. The reason can be found in the lack of interest of the young generation to be involved in a “pro buono” voluntary activity and only the big companies and laboratories are ready to support financially the standard development activities. We are close to a critical situation, when only the “interested” bodies will impose them point of view and the procedure for “consensus voting” by the P-members will become, regrettably, formal an strong influenced by these “interested” global organizations. Now shall be the time when ACOS need to play his coordinative professional role. An example refer to the inertia in adoption for Basic Safety tests a harmonized methodology applicable to all products categories. Which differences exist i.e for heating test or for leakage current measurement, between different products categories? Any difference. But each product standard present his own test method. Useless and confusing. Another example is, as was mentioned already in this discussion, the absence of a harmonized terminology and definition of terms. Same situation is present also in other bodies in which are preferred “committee-administrators rather than technologically-experienced engineering professionals”. Maybe we as professionals with wide and long experience in the field needs now to take a position and to ask IEC, ACOS to “open the eyes” until will be late. I am ready to participate in such Action Group for rescue the Products Safety Engineering from falling in a routine and a “dedicated” (“interested”) process. Maybe this alarm signal can help. Steli Steli Loznen, M.Sc., SM-I Member of IEEE-PSES BoD 17-3 Shaul HaMelech Blvd. 64367 Tel Aviv ISRAEL Tel:+972-3-6912668 Fax:+972-3-6913988 Mobile:+972-54-7245794 E-mail: <mailto:sloz...@ieee.org> sloz...@ieee.org From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: Saturday, January 17, 2015 10:29 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Consistency of safety definitions Rich, (and John, of course!) Thanks for the insight, but not for the “bad news”! Having been a little involved in standards-making in the (dim and distant, it has to be said – see below!), past, it’s got to be sad that those types of influences can prevail in the modern world, especially given the significant overall progress towards global harmonization of requirements. I think a significant part of the problem could be the type of staffing of the national bodies that participate in the standards-making processes – particularly where this includes bureaucrats rather than technologists, because those can be the people who drive the “publish regardless” approach in order to maximise revenues. As an example, when I was a BSI Standards Project Manager for a brief period in 1989-1990, many of the committee secretaries for “technical products” had little or no technical knowledge or experience of the industries which produced those products. Thus the industry-based committee chairmen could drive the standards in the directions that THEY wanted, rather than what would be the best for the industry as a whole – and sometimes it did take some “head-banging” to get standards made with the appropriate technical criteria. I don’t think the situation has improved since then because (having got out of the role because I wanted to get back into industry) when I applied for another similar job back at BSI some years later (after having been made redundant several times), I was told that I was “over-qualified” and that they were really only looking for committee-administrators rather than technologically-experienced engineering types. And, from what you said, I think my take on the UK situation could well be reflected worldwide, and at the “top of the pile” in particular, and so the personal views of the individual committee chairmen can still be override the need for across-the-board harmonization of underlying basic requirements like definitions of earthing and so on. Therefore, I think that it must be for the chairmen of the TC’s (such as 108) to realise and appreciate how their decisions need to be based on “wider pictures” rather than on just the preferences of their own industries. That is especially true where components/assemblies produced by one industry sector are widely used in other sectors – and with the ITE, AV, industrial machinery and control systems, medical (etc., etc.) sectors now using very similar/identical “bu
Re: [PSES] Consistency of safety definitions
Rich, (and John, of course!) Thanks for the insight, but not for the “bad news”! Having been a little involved in standards-making in the (dim and distant, it has to be said – see below!), past, it’s got to be sad that those types of influences can prevail in the modern world, especially given the significant overall progress towards global harmonization of requirements. I think a significant part of the problem could be the type of staffing of the national bodies that participate in the standards-making processes – particularly where this includes bureaucrats rather than technologists, because those can be the people who drive the “publish regardless” approach in order to maximise revenues. As an example, when I was a BSI Standards Project Manager for a brief period in 1989-1990, many of the committee secretaries for “technical products” had little or no technical knowledge or experience of the industries which produced those products. Thus the industry-based committee chairmen could drive the standards in the directions that THEY wanted, rather than what would be the best for the industry as a whole – and sometimes it did take some “head-banging” to get standards made with the appropriate technical criteria. I don’t think the situation has improved since then because (having got out of the role because I wanted to get back into industry) when I applied for another similar job back at BSI some years later (after having been made redundant several times), I was told that I was “over-qualified” and that they were really only looking for committee-administrators rather than technologically-experienced engineering types. And, from what you said, I think my take on the UK situation could well be reflected worldwide, and at the “top of the pile” in particular, and so the personal views of the individual committee chairmen can still be override the need for across-the-board harmonization of underlying basic requirements like definitions of earthing and so on. Therefore, I think that it must be for the chairmen of the TC’s (such as 108) to realise and appreciate how their decisions need to be based on “wider pictures” rather than on just the preferences of their own industries. That is especially true where components/assemblies produced by one industry sector are widely used in other sectors – and with the ITE, AV, industrial machinery and control systems, medical (etc., etc.) sectors now using very similar/identical “building blocks” (e.g. PSUs) to produce significantly different types of end-products, then this is VASTLY more important nowadays than it was 20 yrs ago. Therefore I now ask ALL these chairmen and their committee members to think hard about the wider implications of what they are doing – AND TO TALK TO EACH OTHER AND SORT THESE TYPES OF ISSUES OUT J (Wishful thinking? Maybe but we can hope!) John Allen From: Richard Nute [mailto:ri...@ieee.org] Sent: 17 January 2015 00:11 To: 'John Allen'; EMC-PSTC@LISTSERV.IEEE.ORG; 'John Woodgate' Subject: Consistency of safety definitions Hi John and John: What I have seen is that TCs tend to be myopic. And parochial. And autonomous. And, at times, decide and proceed regardless whether the subject complies with engineering and science. And, driven by IEC rules to publish or lose the work that has been done. Cooperation between TCs, while encouraged, is dependent on individuals who are the liaison. The TCs are comprised of volunteers, who, for the most part, are reluctantly supported by their employer. For many such volunteers, the work is a “cost without a benefit” to the employer. Often, the reward is vicarious for the volunteer. ACOS attempts to drive the use of basic safety standards. It focuses on the topics, does not address definitions, and writes some standards itself. And tends to be all of the above. The only threat ACOS has is to deny work on a new standard. They are reluctant to do this as the IEC makes money through the sale of standards. (The management of TC108 will disagree with my assessment and opinion.) Rich - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy question
[PSES] Consistency of safety definitions
Hi John and John: What I have seen is that TCs tend to be myopic. And parochial. And autonomous. And, at times, decide and proceed regardless whether the subject complies with engineering and science. And, driven by IEC rules to publish or lose the work that has been done. Cooperation between TCs, while encouraged, is dependent on individuals who are the liaison. The TCs are comprised of volunteers, who, for the most part, are reluctantly supported by their employer. For many such volunteers, the work is a “cost without a benefit” to the employer. Often, the reward is vicarious for the volunteer. ACOS attempts to drive the use of basic safety standards. It focuses on the topics, does not address definitions, and writes some standards itself. And tends to be all of the above. The only threat ACOS has is to deny work on a new standard. They are reluctant to do this as the IEC makes money through the sale of standards. (The management of TC108 will disagree with my assessment and opinion.) Rich - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Critical Components definitions
>(who supposedly has been shipping CE marked product to EU on their own for >years "with no issues") Absence of proof of non-compliance is not proof of compliance (or "so what" in short hand :) ) Whilst you're chasing the safety - compare built state subjected to EMC with current build state. Regards Charlie -Original Message- From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com] Sent: 14 March 2014 14:54 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions All makes perfect sense. In the case of a project I have now which is not typical our outsource manufacturer has already gone through the process of obtaining passing EMC and safety reports from their independent agency in the US (who I won't name here but is not an OSHA approved NRTL, they only do CE compliance).Interestingly enough their safety report refers to the critical components list in an annex but they did not initially provide it to me (other annexes were missing as well). Ultimately my company is responsible for the product and the TF so I've been going back and forth with our outsourcer (who supposedly has been shipping CE marked product to EU on their own for years "with no issues") explaining what a critical components list is. Now if none of that makes any sense, I.e. a safety report from a certification agency which includes an empty annex where a critical component list is supposed to be that did not exist at the time the report was written, well it doesn't make sense to me e! ither. -Dave -Original Message- From: Kunde, Brian [mailto:brian_ku...@lecotc.com] Sent: Friday, March 14, 2014 9:10 AM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] Critical Components definitions I have always viewed the Safety Critical Components List (SCCL) as kind of like a Cheat Sheet or Road Map to a safety inspection. As probably most Safety Inspectors, I wouldn't even think about starting a safety evaluation without the SCCL up front. Otherwise, you would be crawling around inside someone's product and probably having to dismantle every part trying to see the manufacturer's name, part number, ratings and hopefully some agency approval marks. Then doing an endless Internet search for the missing information and probably not finding it. I view this as a waist of my time. Internally, on our own products, we include as much information on our SCCLs as we can. We even list components that may technically not be a Safety Critical Components by application, but may make a safety inspections go smoother by including it. For instance, we list every PC board just in case the inspector asks us to show proof of its flammability rating or wants to see the artwork. We include the Rating Label and all warning labels on the SCCL. We even include the part numbers for Schematics that would be helpful to have during an inspection. Over time we have learned what information is helpful to have during an inspection and we try to include that information within the SCCL. Our SCCLs of course includes the manufacturer's name, part number, ratings, and approvals. If a part has special protection requirement we include that. We also include a Web Link to the manufacturer's data sheet if available. If a part does not have agency approvals but is verified as part of our type testing, that is noted on the SCCL. This information is all stored within our components database system and tied to the BOMs of each model of products produced. Our SCCLs becomes part of our internal safety test reports (modeled after the CB test reports). This information is given to Inspectors who will often include our SCCLs within their Field Evaluation reports. Hope this information is helpful. The Other Brian -Original Message- From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com] Sent: Friday, March 14, 2014 8:16 AM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] Critical Components definitions Actually I wasn't just referring to their selection of components (in itself an issue, they pretty much included the entire BOM) but the information in the list. They haven't provided any of the NRTL mark info, critical tech specs, or applicable standards the parts are certified to after repeated requests. I finally got them to provide the manufacturer names and part numbers. -Dave -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Friday, March 14, 2014 3:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] Critical Components definitions In message mailto:d9c1067d2cb544069485d5c3cdbf4...@bn1pr08mb059.namprd08.prod.outlook.com>> , dated Fri, 14 Mar 2014, &
Re: [PSES] Critical Components definitions
All makes perfect sense. In the case of a project I have now which is not typical our outsource manufacturer has already gone through the process of obtaining passing EMC and safety reports from their independent agency in the US (who I won't name here but is not an OSHA approved NRTL, they only do CE compliance).Interestingly enough their safety report refers to the critical components list in an annex but they did not initially provide it to me (other annexes were missing as well). Ultimately my company is responsible for the product and the TF so I've been going back and forth with our outsourcer (who supposedly has been shipping CE marked product to EU on their own for years "with no issues") explaining what a critical components list is. Now if none of that makes any sense, I.e. a safety report from a certification agency which includes an empty annex where a critical component list is supposed to be that did not exist at the time the report was written, well it doesn't make sense to me e! ither. -Dave -Original Message- From: Kunde, Brian [mailto:brian_ku...@lecotc.com] Sent: Friday, March 14, 2014 9:10 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions I have always viewed the Safety Critical Components List (SCCL) as kind of like a Cheat Sheet or Road Map to a safety inspection. As probably most Safety Inspectors, I wouldn't even think about starting a safety evaluation without the SCCL up front. Otherwise, you would be crawling around inside someone's product and probably having to dismantle every part trying to see the manufacturer's name, part number, ratings and hopefully some agency approval marks. Then doing an endless Internet search for the missing information and probably not finding it. I view this as a waist of my time. Internally, on our own products, we include as much information on our SCCLs as we can. We even list components that may technically not be a Safety Critical Components by application, but may make a safety inspections go smoother by including it. For instance, we list every PC board just in case the inspector asks us to show proof of its flammability rating or wants to see the artwork. We include the Rating Label and all warning labels on the SCCL. We even include the part numbers for Schematics that would be helpful to have during an inspection. Over time we have learned what information is helpful to have during an inspection and we try to include that information within the SCCL. Our SCCLs of course includes the manufacturer's name, part number, ratings, and approvals. If a part has special protection requirement we include that. We also include a Web Link to the manufacturer's data sheet if available. If a part does not have agency approvals but is verified as part of our type testing, that is noted on the SCCL. This information is all stored within our components database system and tied to the BOMs of each model of products produced. Our SCCLs becomes part of our internal safety test reports (modeled after the CB test reports). This information is given to Inspectors who will often include our SCCLs within their Field Evaluation reports. Hope this information is helpful. The Other Brian -Original Message- From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com] Sent: Friday, March 14, 2014 8:16 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Actually I wasn't just referring to their selection of components (in itself an issue, they pretty much included the entire BOM) but the information in the list. They haven't provided any of the NRTL mark info, critical tech specs, or applicable standards the parts are certified to after repeated requests. I finally got them to provide the manufacturer names and part numbers. -Dave -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Friday, March 14, 2014 3:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions In message , dated Fri, 14 Mar 2014, "Nyffenegger, Dave" writes: >they don't seem to understand what a critical components list is. I've >given them examples and not gotten very far so I was looking for >something more official like from the standards. Standards writers cannot tell what parts a designer might use and how they might be used. A component could be critical in one circuit but not in another. Bearing in mind what a 'critical component' is (one whose failure, in any way, would compromise safety), one normally examines the schematic and, for each part, considers 'What if...?'. This enquiry must include whether further failures might occur as a consequence of one part failing. Of course, some components are always critical, some, but not all, of those in mains supply
Re: [PSES] Critical Components definitions
All of "our" parts are source controlled either by a drawing or specific Manufacturer's and their specific part numbers. If no drawing, the Manufacturer names and part numbers are loaded in SAP and can only be added/changed by Engineering under ECO control. The purchasing department is only allowed to purchase off the drawing or the specific part number that Engineering controls in SAP unless they have an approved deviation from Engineering which is also recorded in SAP against a part. If they break the rules we go after them with a big stick:) They haven't broken the rules in quite a while. -Dave -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Friday, March 14, 2014 9:35 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions In message , dated Fri, 14 Mar 2014, "Nyffenegger, Dave" writes: >They haven't provided any of the NRTL mark info, critical tech specs, >or applicable standards the parts are certified to after repeated >requests. I finally got them to provide the manufacturer names and >part numbers. It seems that some purchasing departments still have (or assume) freedom to buy parts from any source, so long as they have a vague resemblance to the BOM data. For safety critical components, this is obviously a 'no-no'. But to constrain them, they must be supplied with 'purchasing drawings' which have ALL the details necessary to ensure that the correct parts are purchased. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Critical Components definitions
In message , dated Fri, 14 Mar 2014, "Nyffenegger, Dave" writes: They haven't provided any of the NRTL mark info, critical tech specs, or applicable standards the parts are certified to after repeated requests. I finally got them to provide the manufacturer names and part numbers. It seems that some purchasing departments still have (or assume) freedom to buy parts from any source, so long as they have a vague resemblance to the BOM data. For safety critical components, this is obviously a 'no-no'. But to constrain them, they must be supplied with 'purchasing drawings' which have ALL the details necessary to ensure that the correct parts are purchased. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Critical Components definitions
I have always viewed the Safety Critical Components List (SCCL) as kind of like a Cheat Sheet or Road Map to a safety inspection. As probably most Safety Inspectors, I wouldn't even think about starting a safety evaluation without the SCCL up front. Otherwise, you would be crawling around inside someone's product and probably having to dismantle every part trying to see the manufacturer's name, part number, ratings and hopefully some agency approval marks. Then doing an endless Internet search for the missing information and probably not finding it. I view this as a waist of my time. Internally, on our own products, we include as much information on our SCCLs as we can. We even list components that may technically not be a Safety Critical Components by application, but may make a safety inspections go smoother by including it. For instance, we list every PC board just in case the inspector asks us to show proof of its flammability rating or wants to see the artwork. We include the Rating Label and all warning labels on the SCCL. We even include the part numbers for Schematics that would be helpful to have during an inspection. Over time we have learned what information is helpful to have during an inspection and we try to include that information within the SCCL. Our SCCLs of course includes the manufacturer's name, part number, ratings, and approvals. If a part has special protection requirement we include that. We also include a Web Link to the manufacturer's data sheet if available. If a part does not have agency approvals but is verified as part of our type testing, that is noted on the SCCL. This information is all stored within our components database system and tied to the BOMs of each model of products produced. Our SCCLs becomes part of our internal safety test reports (modeled after the CB test reports). This information is given to Inspectors who will often include our SCCLs within their Field Evaluation reports. Hope this information is helpful. The Other Brian -Original Message- From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com] Sent: Friday, March 14, 2014 8:16 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Actually I wasn't just referring to their selection of components (in itself an issue, they pretty much included the entire BOM) but the information in the list. They haven't provided any of the NRTL mark info, critical tech specs, or applicable standards the parts are certified to after repeated requests. I finally got them to provide the manufacturer names and part numbers. -Dave -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Friday, March 14, 2014 3:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions In message , dated Fri, 14 Mar 2014, "Nyffenegger, Dave" writes: >they don't seem to understand what a critical components list is. I've >given them examples and not gotten very far so I was looking for >something more official like from the standards. Standards writers cannot tell what parts a designer might use and how they might be used. A component could be critical in one circuit but not in another. Bearing in mind what a 'critical component' is (one whose failure, in any way, would compromise safety), one normally examines the schematic and, for each part, considers 'What if...?'. This enquiry must include whether further failures might occur as a consequence of one part failing. Of course, some components are always critical, some, but not all, of those in mains supply circuits. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www
Re: [PSES] Critical Components definitions
Actually I wasn't just referring to their selection of components (in itself an issue, they pretty much included the entire BOM) but the information in the list. They haven't provided any of the NRTL mark info, critical tech specs, or applicable standards the parts are certified to after repeated requests. I finally got them to provide the manufacturer names and part numbers. -Dave -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Friday, March 14, 2014 3:22 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions In message , dated Fri, 14 Mar 2014, "Nyffenegger, Dave" writes: >they don't seem to understand what a critical components list is. I've >given them examples and not gotten very far so I was looking for >something more official like from the standards. Standards writers cannot tell what parts a designer might use and how they might be used. A component could be critical in one circuit but not in another. Bearing in mind what a 'critical component' is (one whose failure, in any way, would compromise safety), one normally examines the schematic and, for each part, considers 'What if...?'. This enquiry must include whether further failures might occur as a consequence of one part failing. Of course, some components are always critical, some, but not all, of those in mains supply circuits. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Critical Components definitions
In message , dated Fri, 14 Mar 2014, "Nyffenegger, Dave" writes: they don't seem to understand what a critical components list is. I've given them examples and not gotten very far so I was looking for something more official like from the standards. Standards writers cannot tell what parts a designer might use and how they might be used. A component could be critical in one circuit but not in another. Bearing in mind what a 'critical component' is (one whose failure, in any way, would compromise safety), one normally examines the schematic and, for each part, considers 'What if...?'. This enquiry must include whether further failures might occur as a consequence of one part failing. Of course, some components are always critical, some, but not all, of those in mains supply circuits. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Critical Components definitions
Yeah, I'm already working on the critical component flag for SAP, but that's another thread, SAP does all our revision control, the doc archives are slaved off of that. I'm working with an outsource manufacturer (US based) on a product they are supplying us for integration. They are also supposed to supply the TF reports and content but they don't seem to understand what a critical components list is. I've given them examples and not gotten very far so I was looking for something more official like from the standards. -Dave -Original Message- From: Brian Oconnell [mailto:oconne...@tamuracorp.com] Sent: Thursday, March 13, 2014 4:36 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Do not know, but in principle should be ok. The 'flagged' components in the company's document control system is typically a superset of the C/C table in safety report. The TF should probably reflect reality(red/blue pill inclusive); that is, tabulate the flagged stuff in the BoM, in addition to including the C/C tables found in the safety and EMC reports. Brian From: Charlie Blackham [mailto:char...@sulisconsultants.com] Sent: Wednesday, March 12, 2014 1:07 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Dave Directive are “higher level” documents that won’t prescribe how you must do things. Tables of “critical components” are typically listed in safety test reports, such as tables for EN 60950 clause 1.5.1. As Rich says, “Critical components lists” are things that help manufacturers in that they allow you to clearly identify components that are “safeguards” . Once you have such a list, flag all included items on your PDM system to (try and) stop second sourcing alternative parts without appropriate checks and sign-off being done first. Don’t just list them in your Technical File, add a flag to your PDM system – that way you have a fighting chance of controlling what happens in reality ☺ Regards Charlie -Original Message- From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com] Sent: 11 March 2014 22:30 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Related to my original question, we normally keep the critical components list in the technical file. Looking at the 2006/42/EC New Machinery Directive Annex VII requirements for the technical file I don't see anything see anything that specifically refers to a critical components list. So I'm wonder where the interpretation of that requirement comes from and the details normally provided in the list. There is a reference " calculation notes, test results, certificates, etc., required to check the conformity of the machinery with the essential health and safety requirements" and " any technical report giving the results of the tests carried out either by the manufacturer or by a body chosen by the manufacturer or his authorised representative,". Are the critical components lists including the manufacturer, their part number, applicable standards and NRTL markings that we normally include in the file for each component being used to fulfill the requirements for the above for purchased critical components? Or is it just customary to include this information in a critical components list and include the list in the technical file? thanks -Dave -Original Message- From: Brian Oconnell [mailto:oconne...@tamuracorp.com] Sent: Monday, February 24, 2014 1:38 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Concur with Mr. Nute. Was once asked to provide a "clear definition of a safety-critical component". To comprise a definition, provided a parametric and descriptive listing of 27 items. The last line was: 27. Any component or material or process that I deem critical to safety and/or critical to a regulatory requirement. Brian -Original Message- From: Richard Nute [mailto:ri...@ieee.org] Sent: Saturday, February 22, 2014 12:13 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Hi Dave: There are no "standard" definitions for critical components. However, do a Google search for "critical components list" and you will find a number of examples and opinions as to a definition of critical components. For example, http://www.tracglobal.com/sites/tracglobal.com/files/pdfs/componentacceptabilityforceproductsafety.pdf I prefer to think of a "critical component" as a "safeguard." A safeguard is a component, part, or assembly that provides protection against one or more hazardous energy sources. Basic insulation, supplementary insulation, and reinforced insulation are safeguards against electric shock. Failure of a safeguard can lead to an injury, or calls into play a supplementary s
Re: [PSES] Critical Components definitions
Do not know, but in principle should be ok. The 'flagged' components in the company's document control system is typically a superset of the C/C table in safety report. The TF should probably reflect reality(red/blue pill inclusive); that is, tabulate the flagged stuff in the BoM, in addition to including the C/C tables found in the safety and EMC reports. Brian From: Charlie Blackham [mailto:char...@sulisconsultants.com] Sent: Wednesday, March 12, 2014 1:07 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Dave Directive are “higher level” documents that won’t prescribe how you must do things. Tables of “critical components” are typically listed in safety test reports, such as tables for EN 60950 clause 1.5.1. As Rich says, “Critical components lists” are things that help manufacturers in that they allow you to clearly identify components that are “safeguards” . Once you have such a list, flag all included items on your PDM system to (try and) stop second sourcing alternative parts without appropriate checks and sign-off being done first. Don’t just list them in your Technical File, add a flag to your PDM system – that way you have a fighting chance of controlling what happens in reality ☺ Regards Charlie -Original Message- From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com] Sent: 11 March 2014 22:30 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Related to my original question, we normally keep the critical components list in the technical file. Looking at the 2006/42/EC New Machinery Directive Annex VII requirements for the technical file I don't see anything see anything that specifically refers to a critical components list. So I'm wonder where the interpretation of that requirement comes from and the details normally provided in the list. There is a reference " calculation notes, test results, certificates, etc., required to check the conformity of the machinery with the essential health and safety requirements" and " any technical report giving the results of the tests carried out either by the manufacturer or by a body chosen by the manufacturer or his authorised representative,". Are the critical components lists including the manufacturer, their part number, applicable standards and NRTL markings that we normally include in the file for each component being used to fulfill the requirements for the above for purchased critical components? Or is it just customary to include this information in a critical components list and include the list in the technical file? thanks -Dave -Original Message- From: Brian Oconnell [mailto:oconne...@tamuracorp.com] Sent: Monday, February 24, 2014 1:38 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Concur with Mr. Nute. Was once asked to provide a "clear definition of a safety-critical component". To comprise a definition, provided a parametric and descriptive listing of 27 items. The last line was: 27. Any component or material or process that I deem critical to safety and/or critical to a regulatory requirement. Brian -Original Message- From: Richard Nute [mailto:ri...@ieee.org] Sent: Saturday, February 22, 2014 12:13 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Hi Dave: There are no "standard" definitions for critical components. However, do a Google search for "critical components list" and you will find a number of examples and opinions as to a definition of critical components. For example, http://www.tracglobal.com/sites/tracglobal.com/files/pdfs/componentacceptabilityforceproductsafety.pdf I prefer to think of a "critical component" as a "safeguard." A safeguard is a component, part, or assembly that provides protection against one or more hazardous energy sources. Basic insulation, supplementary insulation, and reinforced insulation are safeguards against electric shock. Failure of a safeguard can lead to an injury, or calls into play a supplementary safeguard such as supplementary insulation or grounding. The enclosure may be a supplementary safeguard against electric shock or against spread of fire or against both. The point is, you must know the safety function of the component, part, or assembly before you can identify it as a "safeguard" or "critical component." In practice, however, a critical component is any component the certification engineer says is a critical component. Best regards, Rich - 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 All emc-pstc postings are archived and searchable on the web at: http:
Re: [PSES] Critical Components definitions
Dave Directive are "higher level" documents that won't prescribe how you must do things. Tables of "critical components" are typically listed in safety test reports, such as tables for EN 60950 clause 1.5.1. As Rich says, "Critical components lists" are things that help manufacturers in that they allow you to clearly identify components that are "safeguards" . Once you have such a list, flag all included items on your PDM system to (try and) stop second sourcing alternative parts without appropriate checks and sign-off being done first. Don't just list them in your Technical File, add a flag to your PDM system - that way you have a fighting chance of controlling what happens in reality :) Regards Charlie -Original Message- From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com] Sent: 11 March 2014 22:30 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Related to my original question, we normally keep the critical components list in the technical file. Looking at the 2006/42/EC New Machinery Directive Annex VII requirements for the technical file I don't see anything see anything that specifically refers to a critical components list. So I'm wonder where the interpretation of that requirement comes from and the details normally provided in the list. There is a reference " calculation notes, test results, certificates, etc., required to check the conformity of the machinery with the essential health and safety requirements" and " any technical report giving the results of the tests carried out either by the manufacturer or by a body chosen by the manufacturer or his authorised representative,". Are the critical components lists including the manufacturer, their part number, applicable standards and NRTL markings that we normally include in the file for each component being used to fulfill the requirements for the above for purchased critical components? Or is it just customary to include this information in a critical components list and include the list in the technical file? thanks -Dave -Original Message- From: Brian Oconnell [mailto:oconne...@tamuracorp.com] Sent: Monday, February 24, 2014 1:38 PM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] Critical Components definitions Concur with Mr. Nute. Was once asked to provide a "clear definition of a safety-critical component". To comprise a definition, provided a parametric and descriptive listing of 27 items. The last line was: 27. Any component or material or process that I deem critical to safety and/or critical to a regulatory requirement. Brian -Original Message- From: Richard Nute [mailto:ri...@ieee.org] Sent: Saturday, February 22, 2014 12:13 PM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] Critical Components definitions Hi Dave: There are no "standard" definitions for critical components. However, do a Google search for "critical components list" and you will find a number of examples and opinions as to a definition of critical components. For example, http://www.tracglobal.com/sites/tracglobal.com/files/pdfs/componentacceptabilityforceproductsafety.pdf I prefer to think of a "critical component" as a "safeguard." A safeguard is a component, part, or assembly that provides protection against one or more hazardous energy sources. Basic insulation, supplementary insulation, and reinforced insulation are safeguards against electric shock. Failure of a safeguard can lead to an injury, or calls into play a supplementary safeguard such as supplementary insulation or grounding. The enclosure may be a supplementary safeguard against electric shock or against spread of fire or against both. The point is, you must know the safety function of the component, part, or assembly before you can identify it as a "safeguard" or "critical component." In practice, however, a critical component is any component the certification engineer says is a critical component. Best regards, Rich - 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 mailto:emc-p...@ieee.org>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscrib
Re: [PSES] Critical Components definitions
Related to my original question, we normally keep the critical components list in the technical file. Looking at the 2006/42/EC New Machinery Directive Annex VII requirements for the technical file I don't see anything see anything that specifically refers to a critical components list. So I'm wonder where the interpretation of that requirement comes from and the details normally provided in the list. There is a reference " calculation notes, test results, certificates, etc., required to check the conformity of the machinery with the essential health and safety requirements" and " any technical report giving the results of the tests carried out either by the manufacturer or by a body chosen by the manufacturer or his authorised representative,". Are the critical components lists including the manufacturer, their part number, applicable standards and NRTL markings that we normally include in the file for each component being used to fulfill the requirements for the above for purchased critical components? Or is it just customary to include this information in a critical components list and include the list in the technical file? thanks -Dave -Original Message- From: Brian Oconnell [mailto:oconne...@tamuracorp.com] Sent: Monday, February 24, 2014 1:38 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Concur with Mr. Nute. Was once asked to provide a "clear definition of a safety-critical component". To comprise a definition, provided a parametric and descriptive listing of 27 items. The last line was: 27. Any component or material or process that I deem critical to safety and/or critical to a regulatory requirement. Brian -Original Message- From: Richard Nute [mailto:ri...@ieee.org] Sent: Saturday, February 22, 2014 12:13 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Hi Dave: There are no "standard" definitions for critical components. However, do a Google search for "critical components list" and you will find a number of examples and opinions as to a definition of critical components. For example, http://www.tracglobal.com/sites/tracglobal.com/files/pdfs/componentacceptabilityforceproductsafety.pdf I prefer to think of a "critical component" as a "safeguard." A safeguard is a component, part, or assembly that provides protection against one or more hazardous energy sources. Basic insulation, supplementary insulation, and reinforced insulation are safeguards against electric shock. Failure of a safeguard can lead to an injury, or calls into play a supplementary safeguard such as supplementary insulation or grounding. The enclosure may be a supplementary safeguard against electric shock or against spread of fire or against both. The point is, you must know the safety function of the component, part, or assembly before you can identify it as a "safeguard" or "critical component." In practice, however, a critical component is any component the certification engineer says is a critical component. Best regards, Rich - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Critical Components definitions
> From: Brian Oconnell > Sent: Monday, February 24, 2014 10:38 > > Concur with Mr. Nute. Ditto. To add by way of example, there was a recent thread on "regulating network." Components without which or the failure of which the network would lose it regulating function (within the context of the applicable standard) would be deemed critical. Regards, Peter Tarver This email message is for the sole use of the intended recipient(s) and may contain confidential and/or privileged information. If you are not an intended recipient, you may not review, use, copy, disclose or distribute this message. If you received this message in error, please contact the sender by reply email and destroy all copies of the original message. - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Critical Components definitions
Concur with Mr. Nute. Was once asked to provide a "clear definition of a safety-critical component". To comprise a definition, provided a parametric and descriptive listing of 27 items. The last line was: 27. Any component or material or process that I deem critical to safety and/or critical to a regulatory requirement. Brian -Original Message- From: Richard Nute [mailto:ri...@ieee.org] Sent: Saturday, February 22, 2014 12:13 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Critical Components definitions Hi Dave: There are no "standard" definitions for critical components. However, do a Google search for "critical components list" and you will find a number of examples and opinions as to a definition of critical components. For example, http://www.tracglobal.com/sites/tracglobal.com/files/pdfs/componentacceptabilityforceproductsafety.pdf I prefer to think of a "critical component" as a "safeguard." A safeguard is a component, part, or assembly that provides protection against one or more hazardous energy sources. Basic insulation, supplementary insulation, and reinforced insulation are safeguards against electric shock. Failure of a safeguard can lead to an injury, or calls into play a supplementary safeguard such as supplementary insulation or grounding. The enclosure may be a supplementary safeguard against electric shock or against spread of fire or against both. The point is, you must know the safety function of the component, part, or assembly before you can identify it as a "safeguard" or "critical component." In practice, however, a critical component is any component the certification engineer says is a critical component. Best regards, Rich - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Critical Components definitions
Hi Dave: There are no "standard" definitions for critical components. However, do a Google search for "critical components list" and you will find a number of examples and opinions as to a definition of critical components. For example, http://www.tracglobal.com/sites/tracglobal.com/files/pdfs/componentacceptabilityforceproductsafety.pdf I prefer to think of a "critical component" as a "safeguard." A safeguard is a component, part, or assembly that provides protection against one or more hazardous energy sources. Basic insulation, supplementary insulation, and reinforced insulation are safeguards against electric shock. Failure of a safeguard can lead to an injury, or calls into play a supplementary safeguard such as supplementary insulation or grounding. The enclosure may be a supplementary safeguard against electric shock or against spread of fire or against both. The point is, you must know the safety function of the component, part, or assembly before you can identify it as a "safeguard" or "critical component." In practice, however, a critical component is any component the certification engineer says is a critical component. Best regards, Rich - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Critical Components definitions
In message , dated Sat, 22 Feb 2014, John Woodgate writes: I'm primarily looking for the safety related components. Guidelines can only be so general that they probably don't help you at your stage. Instead you need to develop further the skill of detecting safety-critical parts in each product. Look at each part and think 'How can it fail? What if it does (for each way it can fail)? I should have added, but I'm sure you know, is that a failure that does not make the product unsafe is of no significance for compliance with safety standards and regulations, even if the resulting damage makes the product unusable and unrepairable. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Critical Components definitions
In message , dated Sat, 22 Feb 2014, "Nyffenegger, Dave" writes: 'm looking for some more recent definitions/guidelines/criteria for determining what constitutes critical components for the critical component lists in the product technical construction files, in particular the files to be maintained as part of CE compliance. I am not un-familiar with the topic but would like to see what's out there. There are some very old threads regarding this topic in the forum archives so I'm thinking there may be more recent material on this somewhere. I'm primarily looking for the safety related components. Guidelines can only be so general that they probably don't help you at your stage. Instead you need to develop further the skill of detecting safety-critical parts in each product. Look at each part and think 'How can it fail? What if it does (for each way it can fail)? Not only electronic components but mechanical things, especially covers and insulation). Bear in mind that covers and insulation might be omitted in production or when reassembling after repair. Another topic is 'What if that part was substituted by another?' This was a favourite in past designs of consumer product that had a cover secured by four screws. Put a longer one in the front right-hand location and it would impact and break the mains switch, possibly contacting live mains wiring and connecting it to the (Class II, not earthed) metal case. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Nondum ex silvis sumus John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Critical Components definitions
Dave, You pretty well outlined the main concerns for safety critical components. Identifying all the hazards and risks is the first step and then identifying the components relied upon to mitigate those issues is next. As product testing proceeds there may be additional components added. I have certified products with only a handful of critical parts and then others with a list of several dozen. Some may be component parts and others may be outsourced sub-assemblies or purchased parts. There are some obvious choices such as enclosure (material, thickness, etc.), power inlet/outlet modules, brick power supply, fusing, etc. Others may not be so obvious. Outdoor equipment may have thermal performance tied enclosure paint color, high leakage current equipment may have a particular hardware stackup and paint mask for grounding, high voltage resistor feedback strings may have components that are tested for high reliability, you may use conformal coatings for pollution/corrosion control, custom isolation transformers should be qualified and controlled for each manufacturer, circuit networks relied upon for protective impedance must have a controlled schematics and BOMs, and the list goes on. For externally sourced modules and assemblies, it is always best to try for certified materials, appropriate to your application. For example, brick power supply certified to 60950 for OV Cat II may not be appropriate in a product being designed for use in OV Cat III environments. Conversely, I was once involved in a product design which had a large DC rated fuse at a particular point deep inside. It was not relied upon for mains protection but the design engineer felt it would be prudent to include for minimizing damage in the event of an IGBT failure. The fuse cost $70. After completing all of my review and testing for performance, foreseeable faults and abnormal operations, that fuse never opened. Not only did I remove it from the list of critical parts, I gave the engineer the option to remove that fuse from the product. It served no useful purpose. One last point, any components included on your list should also pass through incoming inspection and a minimum list of attributes verified on each part before incorporating them in a product build. This alone is a reason to keep your critical components list as small as possible. But no smaller. Hope this helps. In the end, you will find selecting safety critical parts is a bit of an art. And it is likely that no two safety engineers will produce exactly the same list. Finally, it must be received and approved by your certifying agency. Thanks, - doug Douglas Powell http://www.linkedin.com/in/dougp01 Original Message From: Nyffenegger, Dave Sent: Saturday, February 22, 2014 7:41 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Reply To: Nyffenegger, Dave Subject: [PSES] Critical Components definitions Hi Folks, I'm looking for some more recent definitions/guidelines/criteria for determining what constitutes critical components for the critical component lists in the product technical construction files, in particular the files to be maintained as part of CE compliance. I am not un-familiar with the topic but would like to see what's out there. There are some very old threads regarding this topic in the forum archives so I'm thinking there may be more recent material on this somewhere. I'm primarily looking for the safety related components. There's a lot of threads on EMC critical components. Certainly any components which improper operation or failure could cause unsafe operation of the product would be critical. Then there is the question of the components that could result in other safety concerns such has fire or stored energy release. In particular would we expect to include individual power supplies of commercial equipment (which typically are either integral with the unit or come with it as an external plug in "brick") that are incorporated into the product in the critical components list for example PC power supplies, display monitor power supplies, printer power supplies. I realize this is a subjective issue so any specific citings, white papers, published guidelines from NRTLs or industry experts, etc. would be more useful than opinion. Thanks David P. Nyffenegger, PMP, SM-IEEE Product Development Manager Bell and Howell 3791 South Alston Avenue Durham, NC 27713 Phone: 919.767.6419 Web: www.bellhowell.net - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for grap
[PSES] Critical Components definitions
Hi Folks, I'm looking for some more recent definitions/guidelines/criteria for determining what constitutes critical components for the critical component lists in the product technical construction files, in particular the files to be maintained as part of CE compliance. I am not un-familiar with the topic but would like to see what's out there. There are some very old threads regarding this topic in the forum archives so I'm thinking there may be more recent material on this somewhere. I'm primarily looking for the safety related components. There's a lot of threads on EMC critical components. Certainly any components which improper operation or failure could cause unsafe operation of the product would be critical. Then there is the question of the components that could result in other safety concerns such has fire or stored energy release. In particular would we expect to include individual power supplies of commercial equipment (which typically are either integral with the unit or come with it as an external plug in "brick") that are incorporated into the product in the critical components list for example PC power supplies, display monitor power supplies, printer power supplies. I realize this is a subjective issue so any specific citings, white papers, published guidelines from NRTLs or industry experts, etc. would be more useful than opinion. Thanks David P. Nyffenegger, PMP, SM-IEEE Product Development Manager Bell and Howell 3791 South Alston Avenue Durham, NC 27713 Phone: 919.767.6419 Web: www.bellhowell.net - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
[PSES] Terms and definitions for approvals
Within the implementation of the "goods package" in the EC most ce marking related directives (if not all) are being upgraded to reflect a single way of handling approvals, market surveillance and so on. From the concept NEW EMCD I copied the following definitions to be used in the approvals process for EMCD (and soon others): An NCB (National Certification Body) is more or less equivalent to a Notified Body in the EU and CBTL would be a "Conformity Assesment Body" in the EU (a1) ‘equipment’ means any apparatus or fixed installation; (b2) ‘apparatus’ means any finished appliance or combination thereof made commercially available as a single functional unit, intended for the end user and liable to generate electromagnetic disturbance, or the performance of which is liable to be affected by such disturbance; (c3) ‘fixed installation’ means a particular combination of several types of apparatus and, where applicable, other devices, which are assembled, installed and intended to be used permanently at a predefined location; (d4) ‘electromagnetic compatibility’ means the ability of equipment to function satisfactorily in its electromagnetic environment without introducing intolerable electromagnetic disturbances to other equipment in that environment; (e5) ‘electromagnetic disturbance’ means any electromagnetic phenomenon which may degrade the performance of equipment, including, electromagnetic noise, an unwanted signal or a change in the propagation medium itself; (f6) ‘immunity’ means the ability of equipment to perform as intended without degradation in the presence of an electromagnetic disturbance; (g7) ‘safety purposes’ means the purposes of safeguarding human life or property; (h8) ‘electromagnetic environment’ means all electromagnetic phenomena observable in a given location.; (9) 'making available on the market' means any supply of apparatus for distribution, consumption or use on the Union market in the course of a commercial activity, whether in return for payment or free of charge; (10) 'placing on the market' means the first making available of apparatus on the Union market; (11) 'manufacturer' means any natural or legal person who manufactures apparatus or has apparatus designed or manufactured, and markets that apparatus under his name or trademark; (12) 'authorised representative' means any natural or legal person established within the Union who has received a written mandate from a manufacturer to act on his behalf in relation to specified tasks; (13) 'importer' means any natural or legal person established within the Union who places apparatus from a third country on the Union market; (14) 'distributor' means any natural or legal person in the supply chain, other than the manufacturer or the importer, who makes apparatus available on the market; (15) 'economic operators' means the manufacturer, the authorised representative, the importer and the distributor; (16) 'technical specification' means a document that prescribes technical requirements to be fulfilled by the equipment; (17) 'harmonised standard' means harmonised standard as defined in Article 2(1)(c) of Regulation (EU) No [../..] [on European Standardisation]; (18) 'accreditation' means accreditation as defined in Article 2(10) of Regulation (EC) No 765/2008; (19) 'national accreditation body' means national accreditation body as defined in Article 2(11) of Regulation (EC) No 765/2008; (20) 'conformity assessment' means the process demonstrating whether the requirements relating to an apparatus have been fulfilled; (21) 'conformity assessment body' means a body that performs conformity assessment activities including calibration, testing, certification and inspection; (22) 'recall' means any measure aimed at achieving the return of apparatus that has already been made available to the end user; (23) 'withdrawal' means any measure aimed at preventing apparatus in the supply chain from being made available on the market; (24) 'CE marking' means a marking by which the manufacturer indicates that the apparatus is in conformity with the applicable requirements set out in Union harmonisation legislation providing for its affixing; (25) 'Union harmonisation legislation' means any Union legislation harmonising the conditions for the marketing of products. Regards, Ing. Gert Gremmen, BSc g.grem...@cetest.nl www.cetest.nl Kiotoweg 363 3047 BG Rotterdam T 31(0)104152426 F 31(0)104154953 Before printing, think about the environment. -Oorspronkelijk bericht- Van: emc-p...@ieee.org [mailto:emc-p...@ieee.org] Namens John Woodgate Verzonden: Thursday, January 26, 2012 11:59 PM Aan: EMC-PSTC@LISTSERV.IEEE.ORG On
RE: [PSES] Application of the definitions of the word "hazard"
Rich The hazard is still there because the source thereof still exists – from a Risk Assessment perspective it is then a matter of deciding how often that hazard is likely to cause an accident Very simplistically, in the UK defence field, we generally use a 4 (Severity of perceived actual injury – the Accident) x 6 (Probability of the Accident actually occurring) matrix, per DEF STAN 00-56 and similar stds. (MIL Std 8882 is similar in concept but the terminology & matrix are different) . Therefore, with the un-encased unit there could be a high Probability of the Accident occurring, whilst with the case fitted and properly secured, that Probability is vastly reduced. Thus, from a Risk Assessment perspective, the risk of the Accident is much higher in the first scenario than in the second. However, the expertise of the relevant user also comes into the equation – so whilst Joe Public has relatively little experience to know what the risks are, the trained and experience professional repair man would know the risks and how to take relevant precautions when working on the un-cased unit. There the Risk Assessments for the two people would be significantly different. John Allen London, UK From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of jral...@productsafetyinc.com Sent: 02 November 2010 12:31 To: Richard Nute; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Application of the definitions of the word "hazard" Yes, the mains is a hazard. If the enclosure and insulation mitigate it adequately (I.e. tolerable risk), then no further action is necessary. - Reply message - From: "Richard Nute" List-Post: emc-pstc@listserv.ieee.org Date: Mon, Nov 1, 2010 6:59 pm Subject: [PSES] Application of the definitions of the word "hazard" To: With regard to the use of the word "hazard," consider an equipment supplied from mains. We would all agree that mains is a hazardous energy source (or comprises a hazard). The equipment in question is provided with a suitable enclosure and fully complies with the applicable safety standard. We have a number of definitions for "hazard" from the various posted messages: anything potentially harmful potential for an action with adverse outcome something that can hurt you or do property damage potential source of harm Question: Does the mains within the equipment comprise a hazard? Rich - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher David Heald - 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 All emc-pstc postings are archived and searchable on the web at http://emc-pstc.oc.ieee.org/ 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 Mike Cantwell For policy questions, send mail to: Jim Bacher David Heald
Re: [PSES] Application of the definitions of the word "hazard"
Not only the enclosure and insulation but also the internal circuits providing adequate capacitance discharge or backfeed protection. Peter Merguerian pe...@goglobalcompliance.com Sent from my iPhone On Nov 2, 2010, at 5:31 AM, "jral...@productsafetyinc.com" wrote: Yes, the mains is a hazard. If the enclosure and insulation mitigate it adequately (I.e. tolerable risk), then no further action is necessary. - Reply message - From: "Richard Nute" Date: Mon, Nov 1, 2010 6:59 pm Subject: [PSES] Application of the definitions of the word "hazard" To: With regard to the use of the word "hazard," consider an equipment supplied from mains. We would all agree that mains is a hazardous energy source (or comprises a hazard). The equipment in question is provided with a suitable enclosure and fully complies with the applicable safety standard. We have a number of definitions for "hazard" from the various posted messages: anything potentially harmful potential for an action with adverse outcome something that can hurt you or do property damage potential source of harm Question: Does the mains within the equipment comprise a hazard? Rich - 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 All emc-pstc postings are archived and searchable on the web at: <http://www.ieeecommunities.org/emc-pstc> 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> http://www.ieee-pses.org/ Instructions: <http://listserv.ieee.org/request/user-guide.html> http://listserv.ieee.org/request/user-guide.html List rules: <http://www.ieee-pses.org/listrules.html> http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 < <mailto:emc-p...@ieee.org> emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at <http://www.ieeecommunities.org/emc-pstc> 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/> http://www.ieee-pses.org/ Instructions: <http://listserv.ieee.org/request/user-guide.html> http://listserv.ieee.org/request/user-guide.html List rules: <http://www.ieee-pses.org/listrules.html> http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas < <mailto:emcp...@radiusnorth.net> emcp...@radiusnorth.net> Mike Cantwell < <mailto:mcantw...@ieee.org> mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher < <mailto:j.bac...@ieee.org> j.bac...@ieee.org> David Heald < <mailto:dhe...@gmail.com> dhe...@gmail.com> - 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 All emc-pstc postings are archived and searchable on the web at http://emc-pstc.oc.ieee.org/ 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 Mike Cantwell For policy questions, send mail to: Jim Bacher David Heald
Re: [PSES] Application of the definitions of the word "hazard"
Yes, the mains is a hazard. If the enclosure and insulation mitigate it adequately (I.e. tolerable risk), then no further action is necessary. - Reply message - From: "Richard Nute" List-Post: emc-pstc@listserv.ieee.org Date: Mon, Nov 1, 2010 6:59 pm Subject: [PSES] Application of the definitions of the word "hazard" To: With regard to the use of the word "hazard," consider an equipment supplied from mains. We would all agree that mains is a hazardous energy source (or comprises a hazard). The equipment in question is provided with a suitable enclosure and fully complies with the applicable safety standard. We have a number of definitions for "hazard" from the various posted messages: anything potentially harmful potential for an action with adverse outcome something that can hurt you or do property damage potential source of harm Question: Does the mains within the equipment comprise a hazard? Rich - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher David Heald
Re: [PSES] Application of the definitions of the word "hazard"
Rich, Absolutely YES. The potential for harm continues to exist and is only mitigated by controls (barriers, insulation, clearance and creepage) that can and do fail. Exposure to the hazard whether directly or indirectly may cause harm to the exposed person(s), or cause a fire resulting in potential harm to persons and property. -- Doug Nix, A.Sc.T. PSES Risk Assessment TC Member d...@ieee.org mobile (519) 729-5704 fax (519) 653-1318 Find me LinkedIn at http://www.linkedin.com/in/dougnix Fostering Technological Innovation and Excellence for the Benefit of Humanity. On 1-November-2010, at 19:59, Richard Nute wrote: With regard to the use of the word "hazard," consider an equipment supplied from mains. We would all agree that mains is a hazardous energy source (or comprises a hazard). The equipment in question is provided with a suitable enclosure and fully complies with the applicable safety standard. We have a number of definitions for "hazard" from the various posted messages: anything potentially harmful potential for an action with adverse outcome something that can hurt you or do property damage potential source of harm Question: Does the mains within the equipment comprise a hazard? Rich - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher David Heald
RE: [PSES] Application of the definitions of the word "hazard"
Dear Richie, To the specific question: Does the mains within the equipment comprise a hazard? The answer is YES. But the most important aspect is the evaluation of the Risk associated with the hazard. The Risk can be "acceptable" or "unacceptable". Can a harm (electrocutation) be generated due to mains? Which is the probability that this harm occurs? These are the questions to which shall answer. The hazards (potential source of harm) due especially to mains are: electrical shock, fire. The key for analysis is the EXPOSURE to the hazard (with other words the accessibility to the hazardous areas). If not exist EXPOSURE to the hazard or the probability to access the hazardous areas is very small, the associated Risk is acceptable. Best Regards, Steli Steli Loznen, M.Sc., SM-IEEE I.T.L (Product Testing) Ltd. Q.A & Certification Manager Convener IEC/TC62/SC62A/MT29 1, Bat Sheva St., P.O.Box 87 LOD 71100, ISRAEL Phone:+972-8-9186100 int.203 Fax:+972-8-9153101 Mobile:+972-54-7245794 e-mail: st...@itl.co.il www.itl.co.il -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Tuesday, November 02, 2010 1:59 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Application of the definitions of the word "hazard" With regard to the use of the word "hazard," consider an equipment supplied from mains. We would all agree that mains is a hazardous energy source (or comprises a hazard). The equipment in question is provided with a suitable enclosure and fully complies with the applicable safety standard. We have a number of definitions for "hazard" from the various posted messages: anything potentially harmful potential for an action with adverse outcome something that can hurt you or do property damage potential source of harm Question: Does the mains within the equipment comprise a hazard? Rich - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
RE: [PSES] Application of the definitions of the word "hazard"
Mains is definietely a hazard otherwise you wouldn't need to protect from accessibility. It's the protection from accessibility that reduces the risk of harm to (hopefully) acceptable levels; ie 'within the equipment'. Andy -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: 01 November 2010 23:59 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Application of the definitions of the word "hazard" With regard to the use of the word "hazard," consider an equipment supplied from mains. We would all agree that mains is a hazardous energy source (or comprises a hazard). The equipment in question is provided with a suitable enclosure and fully complies with the applicable safety standard. We have a number of definitions for "hazard" from the various posted messages: anything potentially harmful potential for an action with adverse outcome something that can hurt you or do property damage potential source of harm Question: Does the mains within the equipment comprise a hazard? Rich - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Application of the definitions of the word "hazard"
Not if the equipment design provided single-fault tolerance against exposing the hazard to the operator or the environment where it's used. (i.e. not a fire or a shock hazard unless two things go wrong with the protection) For example, cord connected equipment needs both loss of ground connection and failure of basic insulation from the mains circuit to accessible, conductive parts. Now the hazard comes into existence. ___ _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Engineer From: Richard Nute To: EMC-PSTC@LISTSERV.IEEE.ORG List-Post: emc-pstc@listserv.ieee.org Date: 11/01/2010 04:59 PM Subject:[PSES] Application of the definitions of the word "hazard" With regard to the use of the word "hazard," consider an equipment supplied from mains. We would all agree that mains is a hazardous energy source (or comprises a hazard). The equipment in question is provided with a suitable enclosure and fully complies with the applicable safety standard. We have a number of definitions for "hazard" from the various posted messages: anything potentially harmful potential for an action with adverse outcome something that can hurt you or do property damage potential source of harm Question: Does the mains within the equipment comprise a hazard? Rich - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc <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/ <http://www.ieee-pses.org/> Instructions: http://listserv.ieee.org/request/user-guide.html <http://listserv.ieee.org/request/user-guide.html> List rules: http://www.ieee-pses.org/listrules.html <http://www.ieee-pses.org/listrules.html> For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: This email has been scanned for SPAM content and Viruses by the MessageLabs Email Security System. - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher David Heald
Application of the definitions of the word "hazard"
With regard to the use of the word "hazard," consider an equipment supplied from mains. We would all agree that mains is a hazardous energy source (or comprises a hazard). The equipment in question is provided with a suitable enclosure and fully complies with the applicable safety standard. We have a number of definitions for "hazard" from the various posted messages: anything potentially harmful potential for an action with adverse outcome something that can hurt you or do property damage potential source of harm Question: Does the mains within the equipment comprise a hazard? Rich - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
RE: legally binding definitions and New Approach II (?)
This is a multi-part message in MIME format. The intent is to integrate the content of the 'Decision' into existing New Approach Directives OR to take account of the Decision when those Directvies are next being revised. Work is already underway to take account of the Decision in the on the LVD and EMCD. If you want a catch phrase, it is the NLF - New Legislative Framework. I prefer to call it the New New Approach. Regards Peter. From: emc-p...@ieee.org on behalf of lauren_cr...@amat.com Sent: Sat 10/3/2009 12:13 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: legally binding definitions and New Approach II (?) I might be the last guy on the planet to learn about this "new" legislation >from 2008, but it seems to address some of the discussion we have been having about legally binding definitions. It seems the key legislation is two regulations and a council decision, all related to "marketing products" within scope of the CE marking directives. Unless there is a better catch phrase out there, I think it's fair to call this the "New Approach II" A commission website addresses the overview http://ec.europa.eu/enterprise/regulati n/internal_market_package/index_en.htm. <http://ec.europa.eu/enterprise/regulat on/internal_market_package/index_en.htm> Of course, one can argue about how 'binding" these might be, but the key legislation is Regulation 765/2008, Regulation 764/2008 and Council Decision 768/2008/EC For me, Eur-lex, is the best source for the base document, corrigenda and amendments. http://eur-lex.europa.eu/en/index.htm <http://eur-lex.europa.eu/en/index.htm>I use the "simple search" link in the upper left frame. Regards, Lauren Crane Product Regulatory Analyst Corporate Product EHS Manager Applied Materials Inc. Austin, TX 512 272-6540 [#922 26540] - external use - Save paper and trees! Please consider the environment before printing this e-mail. - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher David Heald - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: Title: RE: legally binding definitions and New Approach II (?) The intent is to integrate the content of the 'Decision' into existing New Approach Directives OR to take account of the Decision when those Directvies are next being revised. Work is already underway to take account of the Decision in the on the LVD and EMCD. If you want a catch phrase, it is the NLF - New Legislative Framework. I prefer to call it the New New Approach. Regards Peter. From: emc-p...@ieee.org on behalf of lauren_cr...@amat.com Sent: Sat 10/3/2009 12:13 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: legally binding definitions and New Approach II (?) I might be the last guy on the planet to learn about this "new" legislation from 2008, but it seems to address some of the discussion we have been having about legally binding definitions. It seems the key legislation is two regulations and a council decision, all related to "marketing products" within scope of the CE marking directives. Unless there is a better catch phrase out there, I think it's fair to call this the "New Approach II" A commission website addresses the overview http://ec.europa.eu/enterprise/regulation/internal_market_package/index_en.htm. <http://ec.europa.eu/enterprise/regulation/internal_market_package/index_en.htm> Of course, one can argue about how 'binding" these might be, but the key legislation is Regulation 765/2008, Regulation 764/2008 and Council Decision 768/2008/EC For me, Eur-lex, is the best source for the base document, corrigenda and amendments. http://eur-lex.europa.eu/en/index.htm <http://eur-lex.europa.eu/en/index
legally binding definitions and New Approach II (?)
I might be the last guy on the planet to learn about this "new" legislation >from 2008, but it seems to address some of the discussion we have been having about legally binding definitions. It seems the key legislation is two regulations and a council decision, all related to "marketing products" within scope of the CE marking directives. Unless there is a better catch phrase out there, I think it's fair to call this the "New Approach II" A commission website addresses the overview http://ec.europa.eu/enterprise/regulati n/internal_market_package/index_en.htm. <http://ec.europa.eu/enterprise/regulat on/internal_market_package/index_en.htm> Of course, one can argue about how 'binding" these might be, but the key legislation is Regulation 765/2008, Regulation 764/2008 and Council Decision 768/2008/EC For me, Eur-lex, is the best source for the base document, corrigenda and amendments. http://eur-lex.europa.eu/en/index.htm <http://eur-lex.europa.eu/en/index.htm>I use the "simple search" link in the upper left frame. Regards, Lauren Crane Product Regulatory Analyst Corporate Product EHS Manager Applied Materials Inc. Austin, TX 512 272-6540 [#922 26540] - external use - Save paper and trees! Please consider the environment before printing this e-mail. - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher David Heald
Re: Bypass and decoupling capacitor definitions.
In message , dated Thu, 17 Apr 2008, Gert Gremmen writes: >Slightly off-topic, but what exactly was >the function of the "pottery capacitor" >that I found in he part list of one of >the far east origine EUT's. It's a simple mistranslation; the correct word is 'ceramic', of course. 'Pottery' is quite common, probably because shorter dictionaries don't include $10 words like 'ceramic'; I've also seen 'earthenware'! -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Murphy's Law has now been officially re-named The Certainty Principle John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Bypass and decoupling capacitor definitions.
Slightly off-topic, but what exactly was the function of the "pottery capacitor" that I found in he part list of one of the far east origine EUT's. I took it as a tribute to Pieter van Musschenbroeck who in a way discovered the capacitor about 25 km from where I live. Gert Gremmen _ Van: emc-p...@ieee.org namens John Woodgate Verzonden: wo 16-4-2008 23:14 Aan: Denomme, Paul S. CC: emc-p...@ieee.org Onderwerp: Re: Bypass and decoupling capacitor definitions. In message , dated Wed, 16 Apr 2008, "Denomme, Paul S." writes: > By decoupling, they are stating the capacitors will supply additional >energy during high frequency gate transitions(high Z) There is no high impedance involved there. The impedance of the capacitor is even lower for those fast transitions than it is for the SMPS hash on the supply lines. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Murphy's Law has now been officially re-named The Certainty Principle John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Bypass and decoupling capacitor definitions.
In message , dated Wed, 16 Apr 2008, "Denomme, Paul S." writes: > By decoupling, they are stating the capacitors will supply additional >energy during high frequency gate transitions(high Z) There is no high impedance involved there. The impedance of the capacitor is even lower for those fast transitions than it is for the SMPS hash on the supply lines. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Murphy's Law has now been officially re-named The Certainty Principle John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Bypass and decoupling capacitor definitions.
I think I determined their definition of decoupling versus bypass. With BC(buried Capacitance) it seems like the BC will act as both a decoupling and a bypass capacitor. By decoupling, they are stating the capacitors will supply additional energy during high frequency gate transitions(high Z) and when they are discussing Bypass they are talking in terms of EMI and eliminating unwanted frequencies (Low Z). So it seems to me they are using the terminology in the correct context. Thanks again to all. Paul Denomme From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of John Woodgate Sent: Wednesday, April 16, 2008 4:33 PM To: emc-p...@ieee.org Subject: Re: Bypass and decoupling capacitor definitions. In message , dated Wed, 16 Apr 2008, "Denomme, Paul S." writes: >Now I have read some papers on buried capacitance and they state you >can remove bypass capacitors on the power distribution system and it >seems that they are using the terms "decoupling" and "bypass" >interchangeably. Would you agree with that assessment? It certainly sounds like it. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Murphy's Law has now been officially re-named The Certainty Principle John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc The information contained in this communication and its attachment(s) is intended only for the use of the individual to whom it is addressed and may contain information that is privileged, confidential, or exempt from disclosure. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify postmas...@viasystems.com and delete the communication without retaining any copies. Thank you. Translations of this available: Traduction disponible chez: Traducciones disponibles en: Vertalingen beschikbaar bij: http://www.viasystems.com/dynamic_page.asp?page_symbol=email_footer - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Bypass and decoupling capacitor definitions.
In message , dated Wed, 16 Apr 2008, "Denomme, Paul S." writes: >Now I have read some papers on buried capacitance and they state you >can remove bypass capacitors on the power distribution system and it >seems that they are using the terms "decoupling" and "bypass" >interchangeably. Would you agree with that assessment? It certainly sounds like it. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Murphy's Law has now been officially re-named The Certainty Principle John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Bypass and decoupling capacitor definitions.
Thank you too all who responded. I believe you all have actually helped me here. I was getting caught up in the semantics a bit myself. I am thinking primarily in the power distribution area and the goal is to decouple the power planes and ground at high frequencies and when you add capacitors between a power plane and a ground plane you achieve this goal. Since a capacitor is actually an L-C circuit in the real world, placing many distributed capacitors over a PDS(Power Distributioin system) you are reducing L which in turn improves the high frequency decoupling between the planes. Now I have read some papers on buried capacitance and they state you can remove bypass capacitors on the power distribution system and it seems that they are using the terms "decoupling" and "bypass" interchangeably. Would you agree with that assessment? Thank you Paul Denomme From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Brian O'Connell Sent: Wednesday, April 16, 2008 2:30 PM To: emc-p...@ieee.org Subject: RE: Bypass and decoupling capacitor definitions. Good point. So I wasted a senior design engineer's time with this one, and his verbage seems similar, but he also said that the two the two terms, while similar, should not be considered interchangeable because bypass indicates a series event and de-couple indicates a parallel event. luck, Brian > -Original Message- > From: John Woodgate [mailto:j...@jmwa.demon.co.uk] > Sent: Wednesday, April 16, 2008 10:19 AM > To: Brian O'Connell > Cc: emc-p...@ieee.org > Subject: Re: Bypass and decoupling capacitor definitions. > > In message <001001c89fe4$18a203d0$d600a...@tamuracorp.com>, > dated Wed, > 16 Apr 2008, Brian O'Connell writes: > >> wel, I borrowed the Pressman book from one of the >> design engineers, >> and it seems to indicate that a decoupling action is, in >> fact, a hi-Z >> action. > > There is always the possibility that someone in the distant > past used > the term 'decoupling' incorrectly, and the error has persisted. > > Elementary thinking is 'voltage-mode' and so if you wanted > to 'decouple' > (reduce coupling) you would include a high series impedance (but the > term 'decouple' isn't, as far as I know, commonly used in > that context). > Shunt capacitors live in the 'current-mode' world, where you reduce > coupling by adding low impedance to earth/ground. > -- > OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk > Murphy's Law has now been officially re-named The Certainty Principle > John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK > > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc The information contained in this communication and its attachment(s) is intended only for the use of the individual to whom it is addressed and may contain information that is privileged, confidential, or exempt from disclosure. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify postmas...@viasystems.com and delete the communication without retaining any copies. Thank you. Translations of this available: Traduction disponible chez: Traducciones disponibles en: Vertalingen beschikbaar bij: http://www.viasystems.com/dynamic_page.asp?page_symbol=email_footer - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Bypass and decoupling capacitor definitions.
Well, you may call them coupling capacitors in the range over which they are intended to transmit the signal without degradation just as you say, but they are blocking caps at lower frequencies. Is the cap between a LISN power conductor and the EMI port a coupling or decoupling (blocking) cap? Depends on what frequency range you are talking about. Ken Javor Phone: (256) 650-5261 > From: John Woodgate > Date: Wed, 16 Apr 2008 19:31:53 +0100 > To: > Subject: Re: Bypass and decoupling capacitor definitions. > > In message , dated Wed, 16 > Apr 2008, Ken Javor writes: > >> Caps used to be used in series in audio amps to block dc from being >> amplified. Caps are used in series in ac-coupled o'scopes. In that >> sense, a cap can be a high impedance decoupler. > > No, those were, and are, called, for obvious reasons, 'coupling > capacitors'. Besides, the coupling only works as intended (unless > differentiation is intended) if the value of the capacitor is low enough > that its charge does not change appreciably during one cycle of the > lowest frequency of interest. If not, loss of gain and waveform > distortion (other than of a sine wave) result. So the capacitor is LOW > impedance compared with the source and load impedances in series. > -- > OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk > Murphy's Law has now been officially re-named The Certainty Principle > John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK > > - > > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list.Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net > Mike Cantwell mcantw...@ieee.org > > For policy questions, send mail to: > > Jim Bacher: j.bac...@ieee.org > David Heald:emc-p...@daveheald.com > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Bypass and decoupling capacitor definitions.
In message <001701c89fef$d3aab7c0$d600a...@tamuracorp.com>, dated Wed,
16 Apr 2008, Brian O'Connell writes:
>but he also said that the two the two terms, while similar, should not
>be considered interchangeable because bypass indicates a series event
>and de-couple indicates a parallel event.
I think I can see what he means ('bypass' = current mode thinking,
'decoupling' = voltage-mode thinking), but I don't think that's helpful.
It's two different ways of thinking about the SAME thing.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
Murphy's Law has now been officially re-named The Certainty Principle
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
-
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Re: Bypass and decoupling capacitor definitions.
In message , dated Wed, 16 Apr 2008, Ken Javor writes: >Caps used to be used in series in audio amps to block dc from being >amplified. Caps are used in series in ac-coupled o'scopes. In that >sense, a cap can be a high impedance decoupler. No, those were, and are, called, for obvious reasons, 'coupling capacitors'. Besides, the coupling only works as intended (unless differentiation is intended) if the value of the capacitor is low enough that its charge does not change appreciably during one cycle of the lowest frequency of interest. If not, loss of gain and waveform distortion (other than of a sine wave) result. So the capacitor is LOW impedance compared with the source and load impedances in series. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Murphy's Law has now been officially re-named The Certainty Principle John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Bypass and decoupling capacitor definitions.
Good point. So I wasted a senior design engineer's time with this one, and his verbage seems similar, but he also said that the two the two terms, while similar, should not be considered interchangeable because bypass indicates a series event and de-couple indicates a parallel event. luck, Brian > -Original Message- > From: John Woodgate [mailto:j...@jmwa.demon.co.uk] > Sent: Wednesday, April 16, 2008 10:19 AM > To: Brian O'Connell > Cc: emc-p...@ieee.org > Subject: Re: Bypass and decoupling capacitor definitions. > > In message <001001c89fe4$18a203d0$d600a...@tamuracorp.com>, > dated Wed, > 16 Apr 2008, Brian O'Connell writes: > >> wel, I borrowed the Pressman book from one of the >> design engineers, >> and it seems to indicate that a decoupling action is, in >> fact, a hi-Z >> action. > > There is always the possibility that someone in the distant > past used > the term 'decoupling' incorrectly, and the error has persisted. > > Elementary thinking is 'voltage-mode' and so if you wanted > to 'decouple' > (reduce coupling) you would include a high series impedance (but the > term 'decouple' isn't, as far as I know, commonly used in > that context). > Shunt capacitors live in the 'current-mode' world, where you reduce > coupling by adding low impedance to earth/ground. > -- > OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk > Murphy's Law has now been officially re-named The Certainty Principle > John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK > > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Bypass and decoupling capacitor definitions.
Paul, I think you are attempting to do the impossible. Definitions varying depending whether one resides in the analog or digital domains or, time or frequency domains or, the UK or the USA, or etc. It is entirely possible for a cap to be both 'Bypassing' and 'Decoupling'. Such caps are also energy reservoirs, inductance killers, anti resonate, and even neutralizing. To try and define by value is also doomed to fail. This category part is neither precise or even stable and is often part of a network where values are deliberately skewed. A 100pf or lower may be used as a bypass at a GHz. Tolerances can be as high as +100% / -50%. Fred Townsend DC to Light Denomme, Paul S. wrote: Hi All, Not sure if this is the right post to ask this question but feedback would be appreciated. Can anyone provide me with the difference between a bypass and decoupling capacitor? My understanding is that bypass caps are used for stabilizing a power supply, and would be used to provide low end AC filtering on a power supply up to a couple hundred MHz and they could be located from the power supply output to being scattered through a board to stabilize the power distribution system and normally have higher than .1uF cap values. Also, decoupling caps would be used local to the ICs on the PCB and provide high frequency noise coupling as well as provide some local power stabilization for the switching noise that will occur due to the high frequency switching of the transistors in the IC. When I looked online for these definitions, it seems like some people are using these terms interchangeably. It may just be semantics, but I am looking for some confirmations from people with a bit more experience on this subject. Thanks in advance for your help. Paul Denomme From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of John McAuley Sent: Thursday, March 13, 2008 12:21 PM To: 'Leber Jody-G19980'; emc-p...@ieee.org Subject: RE: Cigarette Light Adapter Requirements Jody Europe - The following was copied from the Automotive EMC Directive 2004/104/EC. I am not aware of any electrical safety requirements. The voltage will be less than that specified by the LVD? Basically you have radiated emissions, emissions of conducted transients and transient immunity to ISO 7637 standards. In the light of the experience gained since the amendment to Directive 72/245/EEC, it is no longer necessary for after-market equipment unrelated to safety functions to be regulated by a Directive specifically concerning electromagnetic compatibility (EMC) in the automobile sector. For such equipment it is sufficient to obtain a Declaration of Conformity in accordance with the procedures laid down in Council Directive89/336/EEC of 3 May 1989 on the approximation of the laws of the Member States relating to electromagnetic compatibility (3) and in Directive 1999/5/EC of the European Parliament and of the Council of 9 March 1999 on radio equipment and telecommunications terminal equipment and the mutual recognition of their conformity (4). Components sold as aftermarket equipment and intended for the installation in motor vehicles need no typeapproval if they are not related to immunity-related functions (Annex I, 2.1.12). In this case a Declaration of Conformity according to the procedures of Directive 89/336/EEC or 1999/5/EC must be issued. Part of this declaration must be that the ESA fulfils the limits defined in paragraphs 6.5, 6.6, 6.8 and 6.9 of Annex I to this Directive. 6.5. Specification concerning broadband electromagnetic interference generated by ESAs 6.5.1. Method of measurement The electromagnetic radiation generated by the ESA representative of its type shall be measured by the method described in Annex VII. 6.5.2. ESA broadband type-approval limits 6.5.2.1. If measurements are made using the method described in Annex VII, the limits shall be 62 to 52 dB microvolts/ m in the 30 to 75 MHz frequency band, this limit decreasing logarithmically with frequencies above 30 MHz, and 52 to 63 dB microvolts/m in the 75 to 400 MHz band, this limit increasing logarithmically with frequencies above 75 MHz as shown in Appendix 6 to this Annex. In the 400 to 1 000 MHz frequency band the limit remains constant at 63 dB microvolts/m. 6.5.2.2. On the ESA representative of its type, the measured values, expressed in dB microvolts/m, shall be below the type-approval limits. 6.6. Specifications concerning narrowband electromagnetic interference generated by ESAs. 6.6.1. Method of measurement The electromagnetic radiation generated by the ESA representative of its type shall be measured by the method described in Annex VIII. 6.6.2. ESA narrowband type-approval limits 6.6.2.1. If measurements are made using the method described in Annex VIII, the limits shall be 52 to 42 dB microvolts/m in the 30 to 75 MHz frequen
Re: Bypass and decoupling capacitor definitions.
Caps used to be used in series in audio amps to block dc from being amplified. Caps are used in series in ac-coupled o'scopes. In that sense, a cap can be a high impedance decoupler. Ken Javor Phone: (256) 650-5261 > From: John Woodgate > Date: Wed, 16 Apr 2008 18:18:38 +0100 > To: Brian O'Connell > Cc: > Subject: Re: Bypass and decoupling capacitor definitions. > > In message <001001c89fe4$18a203d0$d600a...@tamuracorp.com>, dated Wed, > 16 Apr 2008, Brian O'Connell writes: > >> wel, I borrowed the Pressman book from one of the design engineers, >> and it seems to indicate that a decoupling action is, in fact, a hi-Z >> action. > > There is always the possibility that someone in the distant past used > the term 'decoupling' incorrectly, and the error has persisted. > > Elementary thinking is 'voltage-mode' and so if you wanted to 'decouple' > (reduce coupling) you would include a high series impedance (but the > term 'decouple' isn't, as far as I know, commonly used in that context). > Shunt capacitors live in the 'current-mode' world, where you reduce > coupling by adding low impedance to earth/ground. > -- > OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk > Murphy's Law has now been officially re-named The Certainty Principle > John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK > > - > > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list.Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net > Mike Cantwell mcantw...@ieee.org > > For policy questions, send mail to: > > Jim Bacher: j.bac...@ieee.org > David Heald:emc-p...@daveheald.com > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Bypass and decoupling capacitor definitions.
In message <001001c89fe4$18a203d0$d600a...@tamuracorp.com>, dated Wed, 16 Apr 2008, Brian O'Connell writes: >wel, I borrowed the Pressman book from one of the design engineers, >and it seems to indicate that a decoupling action is, in fact, a hi-Z >action. There is always the possibility that someone in the distant past used the term 'decoupling' incorrectly, and the error has persisted. Elementary thinking is 'voltage-mode' and so if you wanted to 'decouple' (reduce coupling) you would include a high series impedance (but the term 'decouple' isn't, as far as I know, commonly used in that context). Shunt capacitors live in the 'current-mode' world, where you reduce coupling by adding low impedance to earth/ground. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Murphy's Law has now been officially re-named The Certainty Principle John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Bypass and decoupling capacitor definitions.
wel, I borrowed the Pressman book from one of the design engineers, and it seems to indicate that a decoupling action is, in fact, a hi-Z action. Is it semantics, or do we have a fundamental failure of terminology ? R/S, Brian > -Original Message- > From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of John > Woodgate > Sent: Wednesday, April 16, 2008 9:39 AM > To: emc-p...@ieee.org > Subject: Re: Bypass and decoupling capacitor definitions. > > > In message <000601c89fdc$b78d2040$d600a...@tamuracorp.com>, > dated Wed, > 16 Apr 2008, Brian O'Connell writes: > > >In my opinion, the terms should not be interchangeable, and should > >indicate different actions/properties. A bypass will shunt the bad > >signal, so is a lo Z. A decouple is to isolate, so should > be a higher Z > >to the bad stuff. > > No; both must present a LOW impedance to the unwanted currents. > -- > OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk > Murphy's Law has now been officially re-named The Certainty Principle > John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK > > - > --- - > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list.Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net > Mike Cantwell mcantw...@ieee.org > > For policy questions, send mail to: > > Jim Bacher: j.bac...@ieee.org > David Heald:emc-p...@daveheald.com > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Bypass and decoupling capacitor definitions.
In message <000601c89fdc$b78d2040$d600a...@tamuracorp.com>, dated Wed, 16 Apr 2008, Brian O'Connell writes: >In my opinion, the terms should not be interchangeable, and should >indicate different actions/properties. A bypass will shunt the bad >signal, so is a lo Z. A decouple is to isolate, so should be a higher Z >to the bad stuff. No; both must present a LOW impedance to the unwanted currents. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Murphy's Law has now been officially re-named The Certainty Principle John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Bypass and decoupling capacitor definitions.
In message , dated Wed, 16 Apr 2008, "Denomme, Paul S." writes: >Can anyone provide me with the difference between a bypass and >decoupling capacitor? I think there is a difference between US English and British English. Fundamentally, there is no difference; the idea is that the capacitor keeps the voltage across it constant, by diverting alternating currents to where they do no harm, usually earth/ground. In UK, they were all 'decoupling', although it's true that some people drew a distinction between capacitors intended to divert signals, such as a capacitor across an emitter resistor in a BJT amplifier, and those intended to divert other things such as power supply ripple. I think 'bypass' was/is a term more common in US. But whatever you call them, they are there to present a low impedance to the currents you don't want. I don't see any need for two different terms. In the days of valves/tubes, people also had palpitations about such convenient phrases as 'decouple g2 to cathode with a 0.1 uF capacitor'. It's very clear what it means; the capacitor prevents any signal voltage difference between g2 and cathode, and language should serve us; we should not be required to use awkward wording just for pedantry. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Murphy's Law has now been officially re-named The Certainty Principle John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Bypass and decoupling capacitor definitions.
Hi Paul, I'm one of those people who probably uses the words interchangeable. To me, 'bypass' brings to mind *shunting* something to another place, like bypassing IC-generated noise to circuit common, or bypassing circuit noise to chassis. 'Decoupling' makes me think of *separating* two parts of a circuit, like decoupling noise from an IC from getting to the power bus, or preventing power bus noise from reaching an IC. For a component that addresses control loop stability issues, I typically use the word 'compensation'. If you want a more focused audience, consider subscribing to the 'si-list', which deals with signal integrity problems. One web link that looks current is http://www.freelists.org/archives/si-list/ Pat Lawler EMC Engineer SL Power Electronics Corp. paul.deno...@viasystems.com wrote on 04/16/2008 08:41:03 AM: > Not sure if this is the right post to ask this question > but feedback would be appreciated. > > Can anyone provide me with the difference between a bypass and > decoupling capacitor? My understanding is that bypass caps are used > for stabilizing a power supply, and would be used to provide low end > AC filtering on a power supply up to a couple hundred MHz and they > could be located from the power supply output to being scattered > through a board to stabilize the power distribution system and > normally have higher than .1uF cap values. Also, decoupling caps > would be used local to the ICs on the PCB and provide high frequency > noise coupling as well as provide some local power stabilization for > the switching noise that will occur due to the high frequency > switching of the transistors in the IC. > > When I looked online for these definitions, it seems > like some people are using these terms interchangeably. It may just > be semantics, but I am looking for some confirmations from people > with a bit more experience on this subject. > > Thanks in advance for your help. > Paul Denomme - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Bypass and decoupling capacitor definitions.
I asked two power supply design engineers. bypass capacitor - intended to provide a low impedance path for the higher freqs. decoupling capacitor - considered an incorrect term. Note that the wikipedia entry (http://en.wikipedia.org/wiki/Decoupling_capacitor), for what its worth, indicates that the two terms are interchangeable. In my opinion, the terms should not be interchangeable, and should indicate different actions/properties. A bypass will shunt the bad signal, so is a lo Z. A decouple is to isolate, so should be a higher Z to the bad stuff. whatever... luck, Brian From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Denomme, Paul S. Sent: Wednesday, April 16, 2008 8:41 AM To: emc-p...@ieee.org Subject: Bypass and decoupling capacitor definitions. Hi All, Not sure if this is the right post to ask this question but feedback would be appreciated. Can anyone provide me with the difference between a bypass and decoupling capacitor? My understanding is that bypass caps are used for stabilizing a power supply, and would be used to provide low end AC filtering on a power supply up to a couple hundred MHz and they could be located from the power supply output to being scattered through a board to stabilize the power distribution system and normally have higher than .1uF cap values. Also, decoupling caps would be used local to the ICs on the PCB and provide high frequency noise coupling as well as provide some local power stabilization for the switching noise that will occur due to the high frequency switching of the transistors in the IC. When I looked online for these definitions, it seems like some people are using these terms interchangeably. It may just be semantics, but I am looking for some confirmations from people with a bit more experience on this subject. Thanks in advance for your help. Paul Denomme - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Bypass and decoupling capacitor definitions.
Hi All, Not sure if this is the right post to ask this question but feedback would be appreciated. Can anyone provide me with the difference between a bypass and decoupling capacitor? My understanding is that bypass caps are used for stabilizing a power supply, and would be used to provide low end AC filtering on a power supply up to a couple hundred MHz and they could be located from the power supply output to being scattered through a board to stabilize the power distribution system and normally have higher than .1uF cap values. Also, decoupling caps would be used local to the ICs on the PCB and provide high frequency noise coupling as well as provide some local power stabilization for the switching noise that will occur due to the high frequency switching of the transistors in the IC. When I looked online for these definitions, it seems like some people are using these terms interchangeably. It may just be semantics, but I am looking for some confirmations from people with a bit more experience on this subject. Thanks in advance for your help. Paul Denomme From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of John McAuley Sent: Thursday, March 13, 2008 12:21 PM To: 'Leber Jody-G19980'; emc-p...@ieee.org Subject: RE: Cigarette Light Adapter Requirements Jody Europe - The following was copied from the Automotive EMC Directive 2004/104/EC. I am not aware of any electrical safety requirements. The voltage will be less than that specified by the LVD? Basically you have radiated emissions, emissions of conducted transients and transient immunity to ISO 7637 standards. In the light of the experience gained since the amendment to Directive 72/245/EEC, it is no longer necessary for after-market equipment unrelated to safety functions to be regulated by a Directive specifically concerning electromagnetic compatibility (EMC) in the automobile sector. For such equipment it is sufficient to obtain a Declaration of Conformity in accordance with the procedures laid down in Council Directive89/336/EEC of 3 May 1989 on the approximation of the laws of the Member States relating to electromagnetic compatibility (3) and in Directive 1999/5/EC of the European Parliament and of the Council of 9 March 1999 on radio equipment and telecommunications terminal equipment and the mutual recognition of their conformity (4). Components sold as aftermarket equipment and intended for the installation in motor vehicles need no typeapproval if they are not related to immunity-related functions (Annex I, 2.1.12). In this case a Declaration of Conformity according to the procedures of Directive 89/336/EEC or 1999/5/EC must be issued. Part of this declaration must be that the ESA fulfils the limits defined in paragraphs 6.5, 6.6, 6.8 and 6.9 of Annex I to this Directive. 6.5. Specification concerning broadband electromagnetic interference generated by ESAs 6.5.1. Method of measurement The electromagnetic radiation generated by the ESA representative of its type shall be measured by the method described in Annex VII. 6.5.2. ESA broadband type-approval limits 6.5.2.1. If measurements are made using the method described in Annex VII, the limits shall be 62 to 52 dB microvolts/ m in the 30 to 75 MHz frequency band, this limit decreasing logarithmically with frequencies above 30 MHz, and 52 to 63 dB microvolts/m in the 75 to 400 MHz band, this limit increasing logarithmically with frequencies above 75 MHz as shown in Appendix 6 to this Annex. In the 400 to 1 000 MHz frequency band the limit remains constant at 63 dB microvolts/m. 6.5.2.2. On the ESA representative of its type, the measured values, expressed in dB microvolts/m, shall be below the type-approval limits. 6.6. Specifications concerning narrowband electromagnetic interference generated by ESAs. 6.6.1. Method of measurement The electromagnetic radiation generated by the ESA representative of its type shall be measured by the method described in Annex VIII. 6.6.2. ESA narrowband type-approval limits 6.6.2.1. If measurements are made using the method described in Annex VIII, the limits shall be 52 to 42 dB microvolts/m in the 30 to 75 MHz frequency band, this limit decreasing logarithmically with frequencies above 30 MHz, and 42 to 53 dB microvolts/m in the 75 to 400 MHz band, this limit increasing logarithmically with frequencies above 75 MHz as shown in Appendix 7 to this Annex. In the 400 to 1 000 MHz frequency band the limit remains constant at 53 dB microvolts/m. 6.6.2.2. On the ESA representative of its type, the measured value, expressed in dB microvolts/m shall be below the type-approval limits 6.8. Specifications concerning the immunity to transient disturbances conducted along supply lines 6.8.1. Method of testing The immunity of ESA representative of its type shall be tested by the method(s) according to ISO 7637-2:DIS2002 as de
Re: Electricity supply definitions for North America and European Community
Tim, For North American products/equipment you can refer to the "ITI Curve", which is a revised "CBEMA Curve". Dogpile (http://www.dogpile.com) immediately finds: * http://www.pdicorp.com/engineering/SS-ITIC.pdf * http://www.softswitch.com/docs/ (A-1005)%20PAPER%20-%20IEEE%20Cost%20Effective.pdf * http://powerstandards.com/tutorials%5Csagsandswells.htm * http://www.nepsi.com/transients.htm John Barnes KS4GL PE, NCE, ESDC Eng, PSE, SM IEEE dBi Corporation http://www.dbicorporation.com/ This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwellmcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Electricity supply definitions for North America and European Community
Thanks to Neil and Mike for the following Europe EN 50160 and DIN IEC 60038 IEC standard voltage Tim Haynes Electromagnetic Engineering Specialist SELEX Sensors and Airborne Systems Tel: +44 (0) 1582 886239 Fax: +44 (0) 1582 795871 Mobile: e-mail: tim.hay...@selex-sas.com Homepage www.selex-sas.com This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwellmcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Electricity supply definitions for North America and European Community
Tim, I can't help you with North America, although I am sure that some of our colleagues from across there will be able to do that, but for Europe the defining standard is EN 50160. You may still find some deviations covered by Harmonized Documents, especially in the newer states, but that document is the baseline. Best regards Neil R. Barker CEng MIEE FSEE MIEEE Manager Compliance Engineering e2v technologies (uk) ltd 106 Waterhouse Lane Chelmsford Essex CM1 2QU UK Tel: (+44) 1245 453616 Fax: (+44) 1245 453410 Mob: (+44) 7801 723735 From: Haynes, Tim (SELEX) (UK Capability Green) [mailto:tim.hay...@selex-sas.com] Sent: 22 August 2005 11:50 To: EMC-PSTC (E-mail) Subject: Electricity supply definitions for North America and European Community Can anybody point me to references that give the definitions of the electricity supply for North America and the European Community I know that North America use 110Vac 60Hz and that the EU use 230Vac 50Hz but what are the tolerances (EU changed since enlargement?) for voltage and frequency what are definitions of normal supply in respect of brownouts and blackouts. I have been searching on the web but I guess I am using the wrong terminology in the search. Any help out there please? Tim Haynes Electromagnetic Engineering Specialist SELEX Sensors and Airborne Systems Tel: +44 (0) 1582 886239 Fax: +44 (0) 1582 795871 Mobile: e-mail: tim.hay...@selex-sas.com Homepage www.selex-sas.com This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwellmcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Electricity supply definitions for North America and European Community
Tim, I cannot tell for North America, but for the European Community EN 50160 is a good start. Fact sheet here (from a test lab): http://www.reo.co.uk/files/kbase/EN50160.pdf Best regards, Michael Michael Nagel Senior EMC Engineer Motorola GmbH ECC Embedded Communications Computing Lilienthalstrasse 15 85579 Neubiberg/Muenchen - Germany Ph: +49-89-9608-0 Fax: +49-89-9608-2376 e-mail: michael.na...@motorola.com info: http://www.motorola.com/computers From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Haynes, Tim (SELEX) (UK Capability Green) Sent: Montag, 22. August 2005 12:50 To: EMC-PSTC (E-mail) Subject: Electricity supply definitions for North America and European Community Can anybody point me to references that give the definitions of the electricity supply for North America and the European Community I know that North America use 110Vac 60Hz and that the EU use 230Vac 50Hz but what are the tolerances (EU changed since enlargement?) for voltage and frequency what are definitions of normal supply in respect of brownouts and blackouts. I have been searching on the web but I guess I am using the wrong terminology in the search. Any help out there please? Tim Haynes Electromagnetic Engineering Specialist SELEX Sensors and Airborne Systems Tel: +44 (0) 1582 886239 Fax: +44 (0) 1582 795871 Mobile: e-mail: tim.hay...@selex-sas.com Homepage www.selex-sas.com This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwellmcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwellmcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Electricity supply definitions for North America and European Community
Can anybody point me to references that give the definitions of the electricity supply for North America and the European Community I know that North America use 110Vac 60Hz and that the EU use 230Vac 50Hz but what are the tolerances (EU changed since enlargement?) for voltage and frequency what are definitions of normal supply in respect of brownouts and blackouts. I have been searching on the web but I guess I am using the wrong terminology in the search. Any help out there please? Tim Haynes Electromagnetic Engineering Specialist SELEX Sensors and Airborne Systems Tel: +44 (0) 1582 886239 Fax: +44 (0) 1582 795871 Mobile: e-mail: tim.hay...@selex-sas.com Homepage www.selex-sas.com This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwellmcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Translation definitions/expressions of IEC60950
It could be an expensive exercise, but if you look at each of the national adoptions of EN 60950 you should be able to make the same correlations as with the French version. Best regards, Neil R. Barker Compliance Engineering Manager e2v technologies ltd Waterhouse Lane Chelmsford Essex CM1 2QU U.K. Tel: +44 (01245) 453616 Fax: +44 (01245) 453410 E-mail: neil.bar...@e2vtechnologies.com From: Carpentier Kristiaan [mailto:kristiaan.carpent...@thomson.net] Sent: 12 May 2003 11:48 To: Emc-Pstc Subject: Translation definitions/expressions of IEC60950 Dear Group, I am looking for translations of expesssions and definitions used in IEC60950. The french translation is not that difficult to find as it is part of IEC60950, e.g. "SELV" becomes "TBTS", TNV becomes "TRT", etcbut I am more looking for translations into other European languages. Does any-one know a suitable place where this info can be found? Regards, Kris This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Translation definitions/expressions of IEC60950
Hi Kris, in the German version of 60950 the same abbreviations are used as in the English version. e.g. SELV remains SELV and TNV remains TNV. For the translation of the definitions, you have to go into the German version of EN 60950. For definitions in 60950 based on the IEV, you can find the German translation in the IEV. best regards Helmut == Helmut Hintz EMC and Product Safety Lab ZS/OES Alcatel SEL AG Lorenzstrasse 10 70435 Stuttgart Germany Phone: +49 711 821 45809 Fax: +49 711 821 45476 e-mail:helmut.hi...@alcatel.de Carpentier Kristiaan homson.net> cc: Sent by:Subject: Translation definitions/expressions of IEC60950 owner-emc-pstc@majordom o.ieee.org 12.05.2003 12:47 Please respond to Carpentier Kristiaan Dear Group, I am looking for translations of expesssions and definitions used in IEC60950. The french translation is not that difficult to find as it is part of IEC60950, e.g. "SELV" becomes "TBTS", TNV becomes "TRT", etcbut I am more looking for translations into other European languages. Does any-one know a suitable place where this info can be found? Regards, Kris This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Translation definitions/expressions of IEC60950
Dear Group, I am looking for translations of expesssions and definitions used in IEC60950. The french translation is not that difficult to find as it is part of IEC60950, e.g. "SELV" becomes "TBTS", TNV becomes "TRT", etcbut I am more looking for translations into other European languages. Does any-one know a suitable place where this info can be found? Regards, Kris
Re: definitions?
I read in !emc-pstc that Jacob Schanker wrote (in <000c01c27c59$10ee9540$6401a8c0@net1>) about 'definitions?' on Fri, 25 Oct 2002: >How about SI for money - Megadollar, gigadollar, teradollars? The fundamental metric unit of moola is the 'buck'. (;-) -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: definitions?
I read in !emc-pstc that Price, Ed wrote (in ) about 'definitions?' on Fri, 25 Oct 2002: >But I always thought that money was power. Maybe you meant 63 dB$. No, the chamber was made to audiophile specifications (;-). There is more, though. Money = power, but also time = money. So time = power. Energy = time x power = power x power and is therefore measured in square watts. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
RE: definitions?
Since we are dealing with management, i.e. power, the 126dB$ is likely to be based on a lot of dBWhat?s dB$ = 10 log (dBWants/dBWhats) > >Or we could simply do as a friend of mine does and refer to dB(dollar). > >What's that 10 meter chamber cost? About 126 dB(dollar). ;) > > > >Ghery > > > > But I always thought that money was power. Maybe you meant 63 dB$. > > Ed = Best Regards Hans Mellberg Regulatory Compliance & EMC Design Services Consultant By the Pacific Coast next to Silicon Valley, Santa Cruz, CA, USA office:831-454-9450, cell:408-507-9694, fax:831-454-0755 __ Do you Yahoo!? Y! Web Hosting - Let the expert host your web site http://webhosting.yahoo.com/ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: definitions?
I read in !emc-pstc that Ken Javor wrote (in <0h4j00egvta...@mtaout03.icomcast.net>) about 'definitions?' on Fri, 25 Oct 2002: >Excellent point. Don't the Brits refer to 1,000,000,000 as a milliard, or >is that continental usage only? Continental. Forget the old 'Imperial' billion; it's not compatible with metric prefixes and should be allowed to fade away. If in doubt, write 10^9. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
RE: definitions?
>-Original Message- >From: Pettit, Ghery [mailto:ghery.pet...@intel.com] >Sent: Friday, October 25, 2002 12:35 PM >To: 'Jacob Schanker'; Bill Flanigan; emc-p...@majordomo.ieee.org >Subject: RE: definitions? > > > >Or we could simply do as a friend of mine does and refer to dB(dollar). >What's that 10 meter chamber cost? About 126 dB(dollar). ;) > >Ghery > But I always thought that money was power. Maybe you meant 63 dB$. Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
RE: definitions?
Or we could simply do as a friend of mine does and refer to dB(dollar). What's that 10 meter chamber cost? About 126 dB(dollar). ;) Ghery -Original Message- From: Jacob Schanker [mailto:schan...@frontiernet.net] Sent: Friday, October 25, 2002 12:02 PM To: Bill Flanigan; emc-p...@majordomo.ieee.org Subject: Re: definitions? Bill is corrrect, of course, in pointing out this potential source of confusion. Perhaps it explains why the UK has a hard time matching US expenditures - they have to spend 1000 times more to match US billion for billion. Actually, I often hear Europeans use the term "thousand million" to mean 10^9, which avoids confusion. But there is still the matter of a Trillion, which in US parlance is 10^12. Other terms sometimes used: zillion, gazillion. How about SI for money - Megadollar, gigadollar, teradollars? Jack Jacob Z. Schanker, P.E. 65 Crandon Way Rochester, NY 14618 Tel: 585 442 3909 Fax: 585 442 2182 j.schan...@ieee.org - Original Message - From: "Bill Flanigan" To: Sent: Friday, October 25, 2002 12:48 PM Subject: Re: definitions? These definitions could be a problem(dictionary.com) bil·lion n. 1.) The cardinal number equal to 109. 2.) Chiefly British. The cardinal number equal to 1012. 3.) An indefinitely large number. WmFlanigan --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: definitions?
Bill is corrrect, of course, in pointing out this potential source of confusion. Perhaps it explains why the UK has a hard time matching US expenditures - they have to spend 1000 times more to match US billion for billion. Actually, I often hear Europeans use the term "thousand million" to mean 10^9, which avoids confusion. But there is still the matter of a Trillion, which in US parlance is 10^12. Other terms sometimes used: zillion, gazillion. How about SI for money - Megadollar, gigadollar, teradollars? Jack Jacob Z. Schanker, P.E. 65 Crandon Way Rochester, NY 14618 Tel: 585 442 3909 Fax: 585 442 2182 j.schan...@ieee.org - Original Message - From: "Bill Flanigan" To: Sent: Friday, October 25, 2002 12:48 PM Subject: Re: definitions? These definitions could be a problem(dictionary.com) bil·lion n. 1.) The cardinal number equal to 109. 2.) Chiefly British. The cardinal number equal to 1012. 3.) An indefinitely large number. WmFlanigan --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: definitions?
Milliard (F/Nrw/Dan.) or miljard (Sw.) stands for Billion. --- Ken Javor wrote: > > Excellent point. Don't the Brits refer to 1,000,000,000 as a milliard, or > is that continental usage only? > > -- > = Best Regards Hans Mellberg Regulatory Compliance & EMC Design Services Consultant By the Pacific Coast next to Silicon Valley, Santa Cruz, CA, USA office:831-454-9450, cell:408-507-9694, fax:831-454-0755 __ Do you Yahoo!? Y! Web Hosting - Let the expert host your web site http://webhosting.yahoo.com/ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: definitions?
Excellent point. Don't the Brits refer to 1,000,000,000 as a milliard, or is that continental usage only? -- >From: Bill Flanigan >To: emc-p...@majordomo.ieee.org >Subject: Re: definitions? >Date: Fri, Oct 25, 2002, 11:48 AM > > > These definitions could be a problem(dictionary.com) > bil·lion n. > 1.) The cardinal number equal to 109. > 2.) Chiefly British. The cardinal number equal to 1012. > 3.) An indefinitely large number. > > WmFlanigan > > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: emc-p...@hypercom.com > Dave Heald: davehe...@attbi.com > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > http://ieeepstc.mindcruiser.com/ > Click on "browse" and then "emc-pstc mailing list" > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: definitions?
These definitions could be a problem(dictionary.com) bil·lion n. 1.) The cardinal number equal to 109. 2.) Chiefly British. The cardinal number equal to 1012. 3.) An indefinitely large number. WmFlanigan --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
Re: AC, DC definitions and safety
Gregg, I agree with you. Many women have a tendency to use their hands when talking. I only purchase slacks that have pockets (would you believe that they still have womens' slacks without pockets?); however, I have not tried standing on one leg! Let's see, trip and fall and create another unanticipated hazard! taniagr...@msn.com - Original Message - From: Gregg Kervill Sent: Monday, November 19, 2001 7:12 AM To: 'Rich Nute'; 'Product Safety Technical Committee' Subject: RE: AC, DC definitions and safety This works well unless you are working with high voltages (and low power), In my early R&D days I was taught that, if in doubt, (AND AFTER waving an earthed conductor all over the circuit) to keep my left hand in my pocket and stand on my right leg. If something din go horribly wrong the current would not cross the body and was slightly less likely to pass through the heart. Fortunately I never got the 'chance' to prove it true or false - but - hey - any end is better than none. Think of all those "lucky" rabbits feet that have been sold. My answer - if they were that lucky then the rabbit would still be wearing them. Best regards Gregg PLEASE NOTE NEW NUMBERS P.O. Box 310, Reedville, Virginia 22539 USA Phone: (804) 453-3141 Fax: (804) 453-9039 Web: www.test4safety.com -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Rich Nute Sent: Tuesday, November 13, 2001 9:13 PM To: Product Safety Technical Committee Subject: AC, DC definitions and safety Hi Ted: > The electrician's rule of thumb when working on domestic wiring was to > always check the wire is dead, even though you isolated it, in case of > bridging or faulty connection. The technique used was to brush the > exposed conductor lightly with the back of the fingers. Any AC present > will be noticeable as a tingle. DC would cause contraction of hand > muscles which would cause the hand to withdraw from the conductor. The technique of brushing lightly avoids a low- resistance connection to the body which would occur with a tight or solid connection. The back of the hand has more hair, fewer sweat glands, and higher resistance than other parts of the body. So, this, too, tends to avoid a low-resistance connection. Both ac and dc would cause a tingle; in this situation, the protection is by means of a high- resistance connection which limits the current, and the electrician maintains control of his muscles regardless whether ac or dc. > The same teacher explained that this precaution saved lives. Should the > hand be allowed to grasp a live conductor the paralyzing effect of DC > would be more likely to cause injury, shock or death because the effect > of the current on the hand muscles when grasping would increase the grip > and prevent the hand being opened to break the circuit. In this case it > is precisely tetanus of the body which is dangerous because it > interferes with the ability to move away from the hazard. Dc may cause a single contraction, but not continuous contraction. In my experience, the dc tends to throw you away from the source. Charles Dalziel reports in his experiments that his subjects chose not to let go of dc (and they could!) because of the severe pain at the moment of letting go. I studied Reilly (again) and found no reference to tetanization due to dc. Reilly says that "As sinusoidal frequencies approach dc, it becomes quite difficult to stimulate peripheral nerves. Stimulation may be elicited at the onset of direct current as with any rectangular pulse. However, following the onset of direct current, additional stimulation of... skeletal muscle is not so easily achieved..." > Power is hazardous to health in all its forms. I would say that ENERGY is the key parameter, not power. Defibrillators are calibrated in joules, and essentially apply a corrective pulse to the heart to contract the heart muscle and then let it resume normal rythyms. Because we can easily do so, the limits in safety standards are in terms of voltage and current which can be sensed. Sensation levels are very much below the injury level (where energy becomes important). Best regards, Rich ref: Reilly, J. Patrick Applied Bioelectricity from Electrical Stimulation to Electropathology ISBN 0-387-98407-0, Springer-Verlag, New York --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pst
RE: AC, DC definitions and safety
This works well unless you are working with high voltages (and low power), In my early R&D days I was taught that, if in doubt, (AND AFTER waving an earthed conductor all over the circuit) to keep my left hand in my pocket and stand on my right leg. If something din go horribly wrong the current would not cross the body and was slightly less likely to pass through the heart. Fortunately I never got the 'chance' to prove it true or false - but - hey - any end is better than none. Think of all those "lucky" rabbits feet that have been sold. My answer - if they were that lucky then the rabbit would still be wearing them. Best regards Gregg PLEASE NOTE NEW NUMBERS P.O. Box 310, Reedville, Virginia 22539 USA Phone: (804) 453-3141 Fax: (804) 453-9039 Web: www.test4safety.com -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Rich Nute Sent: Tuesday, November 13, 2001 9:13 PM To: Product Safety Technical Committee Subject: AC, DC definitions and safety Hi Ted: > The electrician's rule of thumb when working on domestic wiring was to > always check the wire is dead, even though you isolated it, in case of > bridging or faulty connection. The technique used was to brush the > exposed conductor lightly with the back of the fingers. Any AC present > will be noticeable as a tingle. DC would cause contraction of hand > muscles which would cause the hand to withdraw from the conductor. The technique of brushing lightly avoids a low- resistance connection to the body which would occur with a tight or solid connection. The back of the hand has more hair, fewer sweat glands, and higher resistance than other parts of the body. So, this, too, tends to avoid a low-resistance connection. Both ac and dc would cause a tingle; in this situation, the protection is by means of a high- resistance connection which limits the current, and the electrician maintains control of his muscles regardless whether ac or dc. > The same teacher explained that this precaution saved lives. Should the > hand be allowed to grasp a live conductor the paralyzing effect of DC > would be more likely to cause injury, shock or death because the effect > of the current on the hand muscles when grasping would increase the grip > and prevent the hand being opened to break the circuit. In this case it > is precisely tetanus of the body which is dangerous because it > interferes with the ability to move away from the hazard. Dc may cause a single contraction, but not continuous contraction. In my experience, the dc tends to throw you away from the source. Charles Dalziel reports in his experiments that his subjects chose not to let go of dc (and they could!) because of the severe pain at the moment of letting go. I studied Reilly (again) and found no reference to tetanization due to dc. Reilly says that "As sinusoidal frequencies approach dc, it becomes quite difficult to stimulate peripheral nerves. Stimulation may be elicited at the onset of direct current as with any rectangular pulse. However, following the onset of direct current, additional stimulation of... skeletal muscle is not so easily achieved..." > Power is hazardous to health in all its forms. I would say that ENERGY is the key parameter, not power. Defibrillators are calibrated in joules, and essentially apply a corrective pulse to the heart to contract the heart muscle and then let it resume normal rythyms. Because we can easily do so, the limits in safety standards are in terms of voltage and current which can be sensed. Sensation levels are very much below the injury level (where energy becomes important). Best regards, Rich ref: Reilly, J. Patrick Applied Bioelectricity from Electrical Stimulation to Electropathology ISBN 0-387-98407-0, Springer-Verlag, New York --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at:
AC, DC definitions and safety
Hi Ted: > The electrician's rule of thumb when working on domestic wiring was to > always check the wire is dead, even though you isolated it, in case of > bridging or faulty connection. The technique used was to brush the > exposed conductor lightly with the back of the fingers. Any AC present > will be noticeable as a tingle. DC would cause contraction of hand > muscles which would cause the hand to withdraw from the conductor. The technique of brushing lightly avoids a low- resistance connection to the body which would occur with a tight or solid connection. The back of the hand has more hair, fewer sweat glands, and higher resistance than other parts of the body. So, this, too, tends to avoid a low-resistance connection. Both ac and dc would cause a tingle; in this situation, the protection is by means of a high- resistance connection which limits the current, and the electrician maintains control of his muscles regardless whether ac or dc. > The same teacher explained that this precaution saved lives. Should the > hand be allowed to grasp a live conductor the paralyzing effect of DC > would be more likely to cause injury, shock or death because the effect > of the current on the hand muscles when grasping would increase the grip > and prevent the hand being opened to break the circuit. In this case it > is precisely tetanus of the body which is dangerous because it > interferes with the ability to move away from the hazard. Dc may cause a single contraction, but not continuous contraction. In my experience, the dc tends to throw you away from the source. Charles Dalziel reports in his experiments that his subjects chose not to let go of dc (and they could!) because of the severe pain at the moment of letting go. I studied Reilly (again) and found no reference to tetanization due to dc. Reilly says that "As sinusoidal frequencies approach dc, it becomes quite difficult to stimulate peripheral nerves. Stimulation may be elicited at the onset of direct current as with any rectangular pulse. However, following the onset of direct current, additional stimulation of... skeletal muscle is not so easily achieved..." > Power is hazardous to health in all its forms. I would say that ENERGY is the key parameter, not power. Defibrillators are calibrated in joules, and essentially apply a corrective pulse to the heart to contract the heart muscle and then let it resume normal rythyms. Because we can easily do so, the limits in safety standards are in terms of voltage and current which can be sensed. Sensation levels are very much below the injury level (where energy becomes important). Best regards, Rich ref: Reilly, J. Patrick Applied Bioelectricity from Electrical Stimulation to Electropathology ISBN 0-387-98407-0, Springer-Verlag, New York --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
AC, DC definitions and safety
my two cents worth About electric shock: I'm finding it hard to reconcile some of what I'm reading here with real world experience of electric shock, not saying anyone's wrong, just that evidence is open to interpretation. In particular the statement "Dc does not cause either tetanus or fibrillation" seems to be contrary to common experience, I'm using the meaning of 'tetanus' to be paralysis and 'fibrillation' as uncontrolled motion. The electrician's rule of thumb when working on domestic wiring was to always check the wire is dead, even though you isolated it, in case of bridging or faulty connection. The technique used was to brush the exposed conductor lightly with the back of the fingers. Any AC present will be noticeable as a tingle. DC would cause contraction of hand muscles which would cause the hand to withdraw from the conductor. The same teacher explained that this precaution saved lives. Should the hand be allowed to grasp a live conductor the paralyzing effect of DC would be more likely to cause injury, shock or death because the effect of the current on the hand muscles when grasping would increase the grip and prevent the hand being opened to break the circuit. In this case it is precisely tetanus of the body which is dangerous because it interferes with the ability to move away from the hazard. The effect of AC on the hand was not described at the time but the implication was that a similar amplitude AC shock would be less hazardous to health. The basic studies of the nervous system made long ago used crude voltaic cells (DC) across muscle tissue to demonstrate muscle action by electrical stimulation. Try it yourself and then see if you agree that DC causes neither tetanus nor fibrillation! Definition of DC for test purposes: I wonder if I've missed the point or not? Maybe the rules and instructions were written in good faith with the expectation that safety evaluation would include recognition of the intent of the designer and the purpose of the circuit. When the purpose of the circuit is to handle power (not information) then it doesn't matter what the power signal format is, AC or DC, low or high frequency, any mark-space ratio. Power is hazardous to health in all its forms. It would seem to be in bad faith to ask what the definition of DC is for safety purposes if the intent of the evaluation is to promote safety. Best Regards Ted Rook Crest Audio 201 909 8700 ext 213 --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: Definitions - Safety Critical, Safety Circuit
My experience agrees with yours Gert - there is no simple formula to follow. In my early days as a PSE I tried to draw a flow-diagram of product safety assessment and decisions. On the first line I had about 20 options and each of those dropped down to about 20 more - many of which interlocked.after a couple of weeks I gave up. I believe there is a real danger when one tries to provide general guidance. There will always be exceptions - hence standardization and harmonization will (I believe) never satisfy all conditions. When I write product descriptions I deliberately over specify the safety aspects of critical components - or systems. There is one reason for this - to ensure that everyone on the project understands the impact of changing components. When the PD is cut down my the agency I send a file copy of my original for the manufacturing/design file. That way there is a history. (e.g. if I use an HB enclosure because the product if powered from and SELVEL PSU with current fold-back, then that goes into the general description AND the description of the PSU.) I get despondent reading some agency reports to do not include that level of detail - but a telephone call to the manufacturer usually gets the answer. I know that not everyone does writes descriptions the way I do and I am not suggesting that it is the best way (or ought to be standardized) - it just happens to work for me and my clients. Best regards Gregg P.O. Box 310 Reedville, Virginia 22539 Phone: (804) 453-3141 Fax: (804) 453-9039 Web:www.test4safety.com -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of CE-test - Ing. Gert Gremmen - ce-marking and more... Sent: Thursday, November 08, 2001 2:13 AM To: Doug McKean; EMC-PSTC Discussion Group Subject: RE: Definitions - Safety Critical, Safety Circuit Hi Dough, Group, I agree that is approach is much more simple to understand, but most definitions up to now have the problem of defining A LOT of components as safety critical. The safety critical parts need much more attention then just specification and name it. They need to be maintained in brand , type and material f.a. If an ECO (Engineering Change Order) is made, replacing a safety critical component needs re-assessment of the whole safety concept. Safety related components need however just fulfill their safety specs and they will do the job, and ordinary components may be replaced at will by the manufacturer by any other part that does the functional job. A similar reasoning can be made to measures, procedures, circuits (build from components) and construction. The approch i treid in an eralier mail made use of the double layer concept in safety (electrical mechanical chemical radiation heat and fire) to identify components. Those who bridge two layers of safety, or can invalidate the safety of a circuit are Safety Critical. (f.a. a cap that goes from hazardous voltageto an ungrounded accessible part) Those that bridge only one layer are Safety Related. (f.a. one of the two insulations in double insulation) Those that are redundant (from safety point of view) are ordinary components. What do you think of this: can this approach simplify the job ? Regards, Gert Gremmen, (Ing) ce-test, qualified testing === Web presence http://www.cetest.nl CE-shop http://www.cetest.nl/ce_shop.htm /-/ Compliance testing is our core business /-/ === >>-Original Message- >>From: owner-emc-p...@majordomo.ieee.org >>[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Doug McKean >>Sent: Thursday, November 08, 2001 4:07 AM >>To: EMC-PSTC Discussion Group >>Subject: Re: Definitions - Safety Critical, Safety Circuit >> >> >> >>Couldn't we just go to the front of the UL1950/60950 >>standard and agree that a "safety critical part or device >>or circuit or construction" is simply something used >> >>"... >>to prevent injury or damage due to: >>- Electric shock hazard >>- Energy hazards >>- Fire hazard >>- Mechanical hazard >>- Heat hazard >>- Radiation hazard >>- Chemical hazard >>..." >> >>Regards, Doug McKean >> >> >> >>--- >>This message is from the IEEE EMC Society Product Safety >>Technical Committee emc-pstc discussion list. >> >>Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ >> >>To cancel your subscription, send mail to: >> majord...@ieee.org >>with the single line: >> unsubscribe emc-pstc >> >>For help, send mail to the list administrators: >> Michael Garretson:pstc_ad...@garretson.org >&g
RE: Definitions - Safety Critical, Safety Circuit
Hi Dough, Group, I agree that is approach is much more simple to understand, but most definitions up to now have the problem of defining A LOT of components as safety critical. The safety critical parts need much more attention then just specification and name it. They need to be maintained in brand , type and material f.a. If an ECO (Engineering Change Order) is made, replacing a safety critical component needs re-assessment of the whole safety concept. Safety related components need however just fulfill their safety specs and they will do the job, and ordinary components may be replaced at will by the manufacturer by any other part that does the functional job. A similar reasoning can be made to measures, procedures, circuits (build from components) and construction. The approch i treid in an eralier mail made use of the double layer concept in safety (electrical mechanical chemical radiation heat and fire) to identify components. Those who bridge two layers of safety, or can invalidate the safety of a circuit are Safety Critical. (f.a. a cap that goes from hazardous voltageto an ungrounded accessible part) Those that bridge only one layer are Safety Related. (f.a. one of the two insulations in double insulation) Those that are redundant (from safety point of view) are ordinary components. What do you think of this: can this approach simplify the job ? Regards, Gert Gremmen, (Ing) ce-test, qualified testing === Web presence http://www.cetest.nl CE-shop http://www.cetest.nl/ce_shop.htm /-/ Compliance testing is our core business /-/ === >>-Original Message- >>From: owner-emc-p...@majordomo.ieee.org >>[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Doug McKean >>Sent: Thursday, November 08, 2001 4:07 AM >>To: EMC-PSTC Discussion Group >>Subject: Re: Definitions - Safety Critical, Safety Circuit >> >> >> >>Couldn't we just go to the front of the UL1950/60950 >>standard and agree that a "safety critical part or device >>or circuit or construction" is simply something used >> >>"... >>to prevent injury or damage due to: >>- Electric shock hazard >>- Energy hazards >>- Fire hazard >>- Mechanical hazard >>- Heat hazard >>- Radiation hazard >>- Chemical hazard >>..." >> >>Regards, Doug McKean >> >> >> >>--- >>This message is from the IEEE EMC Society Product Safety >>Technical Committee emc-pstc discussion list. >> >>Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ >> >>To cancel your subscription, send mail to: >> majord...@ieee.org >>with the single line: >> unsubscribe emc-pstc >> >>For help, send mail to the list administrators: >> Michael Garretson:pstc_ad...@garretson.org >> Dave Healddavehe...@mediaone.net >> >>For policy questions, send mail to: >> Richard Nute: ri...@ieee.org >> Jim Bacher: j.bac...@ieee.org >> >>All emc-pstc postings are archived and searchable on the web at: >>No longer online until our new server is brought online and >>the old messages are imported into the new server. >> >> <>
Re: Definitions - Safety Critical, Safety Circuit
Couldn't we just go to the front of the UL1950/60950 standard and agree that a "safety critical part or device or circuit or construction" is simply something used "... to prevent injury or damage due to: - Electric shock hazard - Energy hazards - Fire hazard - Mechanical hazard - Heat hazard - Radiation hazard - Chemical hazard " Regards, Doug McKean --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Definitions - Safety Critical, Safety Circuit
Group, I pulled these from Cigital labs web site. A good first crack at definitions that perhaps the "community" could agree on. I am familiar with MIL-HDBK-882C and have used it on several occasions to evaluate things that go boom in a loud way. This is generally considered "BAD" by those in close proximity to the event. The details are left to the skill and experience of a competent safety engineer to ensure that those in close proximity are "them" and not "us". Safety-Critical A term applied to a condition, event, operation, process, object, function or system whose proper recognition, control, performance or tolerance is essential to safe system operation or use; e.g., safety critical function, safety critical path, safety critical component (882C). Safety Circuit A single, or a network of, simple circuit element(s) which are required to function in the support or enabling of a safety function. Where a simple circuit element is the mathematical model of a two terminal device, or function, which cannot be further subdivided into other two-terminal devices, or functions. Best regards, Daniel E. Teninty, P.E. Managing Partner DTEC Associates LLC http://www.dtec-associates.com Streamlining the Compliance Process 5406 S. Glendora Drive Spokane, WA 99223 (509) 443-0215 (509) 443-0181 fax --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: conductive part definitions
Peter, Here's my two cents ... Extraneous/non-electrical Conductive Part - 1 A conductive part that is not intended to be part of ANY electrical circuit (power or otherwise) of a device. 2. If removed from the device, does not cause any degradation of electrical performance. 3. Has a high enough conductance so that if energized with a single mode fault from the lines voltage for device, would cause current to flow in excess of 5 mA. Remove item #3 above for "Extraneous Conductive Part". On Wed, 17 Mar 1999, Peter E. Perkins wrote: > I'm involved in a discussion concerning definitions... wot's you > opinion... > > Exposed conductive part: conductive part of equipment, which can be > touched and which is not normally live, but which can become live when > basic insulation fails. > > Extraneous/non-electrical conductive part: conductive part not > forming part of the electrical installation and liable to introduce an > electric potential, generally the electric potential of a local earth. > > The issue is with the name of the last definition. Is it clearer > to call it an 'Extraneous conductive part' or call it a 'Non-electrical > conductive part'? Why do you prefer one name over the other? > > Keep those cards and letters coming, folks... we'll tally the > votes and let you know how it comes out... - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: conductive part definitions
Hi Pete: It seems to me that there are several kinds of conductive parts that we need to be concerned about from a safety perspective: 1. Energized parts at hazardous voltage. 2. Energized parts at non-hazardous voltage. 3. Energized parts at non-hazardous current. 4. Grounded/earthed parts. 5. Non-grounded/earthed parts susceptible of becoming energized at a hazardous voltage in the event of a fault. 6. Non-grounded/earthed parts not susceptible of becoming energized at hazardous voltage in the event of a fault. For the purpose of these definitions, grounded/earthed is taken as meaning bonded to the earth. Non-grounded/earthed is taken as meaning not bonded to the earth, but may be incidentally connected to earth (i.e., not connected to earth in a manner that assures a current- carrying capability). Each of the preceding parts can be either accessible or inaccessible. (The safety standards prohibit some of these parts from being accessible.) According to your definitions: > Exposed conductive part: conductive part of equipment, which can be > touched and which is not normally live, but which can become live when > basic insulation fails. Exposed conductive part = My definition 5, and accessible. > Extraneous/non-electrical conductive part: conductive part not > forming part of the electrical installation and liable to introduce an > electric potential, generally the electric potential of a local earth. Extraneous/non-electrical conductive part = My definition 6. Your question: Which is a better term for the definition, extraneous or non-electrical? In the sense of this discussion, a conductive part is implied to be an electrically-conductive part. So, a non-electrical electrically-conductive part could be taken as an oxymoron. Its certainly not clear as to what is meant. Let's review Webster's Collegiate Tenth: Extraneous: 1) existing on or coming from the outside; 2a) not forming an essential or vital part; 2b) having no relevance; 3) being a number obtained in solving an equation that is not a solution to the equation. So, it seems the word "extraneous" is consistent with the definition of the part. Best regards, Rich - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
conductive part definitions
PSNet I'm involved in a discussion concerning definitions... wot's you opinion... Exposed conductive part: conductive part of equipment, which can be touched and which is not normally live, but which can become live when basic insulation fails. Extraneous/non-electrical conductive part: conductive part not forming part of the electrical installation and liable to introduce an electric potential, generally the electric potential of a local earth. The issue is with the name of the last definition. Is it clearer to call it an 'Extraneous conductive part' or call it a 'Non-electrical conductive part'? Why do you prefer one name over the other? Keep those cards and letters coming, folks... we'll tally the votes and let you know how it comes out... :>) br, Pete Perkins - - - - - Peter E Perkins Principal Product Safety Consultant Tigard, ORe 97281-3427 +1/503/452-1201 phone/fax p.perk...@ieee.org email visit our website: http://ourworld.compuserve.com/homepages/peperkins - - - - - - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: Various Circuit definitions
Hello Arjen: The definitions for Class 2 and Class 3 circuits may be found in the USA National Electrical Code, NFPA 70: Article 725-2 Definitions. Article 725-41(a) Power sources for Class 2 and Class 3 circuits. Figure 725.41 Class 2 and Class 3 circuits. Tables 11(a) Class 2 and Class 3 Alternating- current power source limitations. Tables 11(b) Class 2 and Class 3 Direct-current power source limitations. The index has an entry for: Energy-limited, Class 2 and Class 3 control and signal circuits [Article 725-41]. I cannot find any other mention of either Limited Energy or Energy-Limited that apply to Class 2 and Class 3 circuits. Article 725-41(a)(4) references UL 1950. The specific reference would be Sub-clause 2.11, Limited Power Sources. I suspect this may answer your question as worded, but I suspect it does not answer what you want to know. If you will be more specific, I will try to answer your question. Best wishes for the holiday season, Rich - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Various Circuit definitions
I am looking for exact definitions of Class 2 and Class 3 circuits, as well as Limited Energy circuits in the context of both the Canadian (CEC) and American (NEC) realms. I am especially finding the NEC definitions difficult to pin down - maybe just looking in the wrong section? Can anyone help me with either the definitions, or a good resource on where to get a good definition? Arjen Dragt Compliance Engineering Inverpower Controls Ltd. Phone: (905) 639-4693 Ext. 211 Fax: (905) 639-2918
voltage definitions
To expand on Peter Perkins answer of voltage definitions, it depends on what country and standard you are referring to. With the acceptance of IEC standards (i.e. IEC 1010) these voltages are becoming more standard but there are still differences such as CSA C22.2 - 147 which defines ELV (extra low voltage) as 30 rms and 42.4 peak. So don't assume all ELV are equal until you check the definition. eric
Environment Definitions Response Summary
Hello again to all of you, First, thanks to the 3 that responded. I wrote the following inquiry, marked with '>': -- >I can fairly easily characterize the household, commercial, light-industrial, and >heavy-industrial environments, but I have not found any clear and official definitions >of these type of environments. The one official source that I have been able to find is >EN50082-1 which only provides a few examples. What is the delineation between >light-industrial and heavy-industrial? >Is/are there any published standards/publications/documents that define >these environments? If there are any and any of you know them, would you be >kind enough to relay that information to me. All that I need are the >standards references, but the actual definitions would be also appreciated. -- >From the responses that I received, there appears that there are no actual clear definitions for any of these categories. All of the respondents provided their own interpretations by stating that the delineation occurs with use of the public low-voltage mains supply (minimally, refer to Section 1 of EN50082-1). Only one actually referred to a standard and only one referred to other environmental factors. I feel that all of these respondents are correct with the responses to this query. However, to ensure adequate application, one must look to the standards. From the standard I am absolutely sure that there must be some exceptions to this. referred to above, the only description of delineation of these categories is the public low-voltage mains supply and those locations serviced by it. If an apparatus does directly connect to the public low-voltage mains supply, it must then be classified as residential, commercial or light-industrial. All other apparatus are covered by other standards. However, in many cases, exceptions (or gray-areas) exist for every rule (e.g., floor supervisor office areas in steel mills, etc.) which is why there is so much interpretation, I suppose. With the apparatus' descriptions and gray-areas, the standards can only provide 'guidelines' for installed environments. It is then up to the manufacturer/integrator/etc. to determine the actual installed environment for its apparatus and then to test it accordingly. Again, thanks to the 3 that took the time to respond to my query. Constructive comments are always welcome. Best regards, Ron Pickard r...@syntellect.com
Environment Definitions
Hello again to all of you, I can fairly easily characterize the household, commercial, light-industrial, and heavy-industrial environments, but I have not found any clear and official definitions of these type of environments. The one official source that I have been able to find is EN50082-1 which only provides a few examples. What is the delineation between light-industrial and heavy-industrial? Is/are there any published standards/publications/documents that define these environments? If there are any and any of you know them, would you be kind enough to relay that information to me. All that I need are the standards references, but the actual definitions would be also appreciated. If anyone else is interested, I will summarize and post the feedback I get back. Best regards, Ron Pickard r...@syntellect.com
