RE: CLASS 11(DOUBLE INSULATED) 2/3-CORE CABLE
Could the grounding safety issues we are confronted by have been avoided if the incoming AC supply had remained 'balanced' that is, not referenced to local ground anywhere? Or to put it another way. Some where along the way it was decided to ground the neutral at the premises entrance. Why? What is the advantage? and to whom? I feel I should already know the answer, but I don't. Any offers? (which reminds me of the fact that it was the catalog of an American parts supplier which taught me why we have fused domestic plugs in the UK and not elsewhere; because the UK domestic wiring uses ring distribution through the house. The ring has a single thirty amp rated fuse and so can supply over twice the current rating of an individual outlet. Primary protection takes place inside the appliance outlet plug which has 13A fuse rating. The resettable magnetic breakers that are so familiar to everyone in 120V territory are unknown in the UK.) Newbie here. Brit working in US. Best Regards Ted Rook Crest Audio 201 909 8700 ext 213 geor...@lexmark.com 05-Nov-01 1:46:15 PM Several years ago I had the need to explain this same issue. Similarly most of the inquiries came from the U.K. Here are some exerpts from a white paper done to address this issue: *** This document addresses the nature and safety of two-wire ITE products. The international safety standard for ITE is IEC 60950. The referenced sections of IEC 60950 below are generally the same in unique country standards. SHOCK PROTECTION A major aspect of product safety for ITE is protection against electric shock. There are three equally acceptable methods of achieving this protection (section 1.2.4). Class I equipment employs only basic insulation, but ties all accessible conductive parts to a ground pin to protect the user in the event of a failure of the basic insulation. Such equipment requires a three-wire line cord and a reliable path to earth ground. Class II equipment uses double or reinforced insulation between primary voltage and accessible conductive parts to protect against electric shock. Such equipment uses a two-wire line cord, is not dependent on the integrity of the building's grounding system, and typically displays the square within a square symbol denoting double insulation. ITE products which contain no hazardous voltages (e.g. less than 42.4Vpk/60Vdc) are approved as Class III devices. NATURE OF CLASS II There is one aspect of Class II equipment that can confuse end users. Because no earth ground path is required or available, accessible conductive parts will float to some voltage less than the applied mains voltage. Typically this may be one-half of the mains voltage. This voltage is not considered a hazard under the standards as the available current cannot exceed the 250uA specified in Table 17 of section 5.2.2. Some individuals may be able to feel a slight tingle or shock at this low current level, although no electric shock injury should result. FINAL COMMENTS If a user is aware of a voltage on an accessible part, and suspects a hazardous condition, some simple tests can be performed to eliminate this concern. George Alspaugh --- 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: 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: CLASS 11(DOUBLE INSULATED) 2/3-CORE CABLE
REMEMBER THE EMC FILTER! --- 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: CLASS 11(DOUBLE INSULATED) 2/3-CORE CABLE
I read in !emc-pstc that geor...@lexmark.com wrote (in 200111051917.OAA 13...@interlock2.lexmark.com) about 'CLASS 11(DOUBLE INSULATED) 2/3-CORE CABLE', on Mon, 5 Nov 2001: A word of history on Class I vs. Class II, as I understand it. In the beginning there was no such thing as earth grounding in homes and offices for the needed electrical appliances. The equivalent of our present double insulation was required to prevent against electric shock. No, those old products were 'Class 0' - basic insulation only. Class 0 is banned in most countries now. Looking inside one of those old products makes you shudder now. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- 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: CLASS 11(DOUBLE INSULATED) 2/3-CORE CABLE
I read in !emc-pstc that Andrew Wood andrew.w...@landinst.com wrote (in e49d8b319a2fd5119e2808002bc33c591c8...@landuk1.landinst.com) about 'CLASS 11(DOUBLE INSULATED) 2/3-CORE CABLE', on Mon, 5 Nov 2001: All I have a piece of equipment falling under the scope of EN6010. Is that a typo or do you really think that is the number? To set the scene it is a low volume product, approx 0.5m cube, stainless steel enclosure and will sit on a bench in food cold storage areas. Mains lead connects via IP68 connector. It incorporates a SMPS for universal mains operation ( current draw approx 0.3A). Because of problems ensuring a reliable earth in some locations for its predecessor, I have specifically designed it to be Class2 (double insulated). Therefore safe for all markets. Now, ironically, I am encountering some unease with the UK sales dept. After all everyone KNOWS that a metal box should be earthed. (I don't dismiss this attitude lightly because it is no doubt shared by some of the customer base.) Technically there is no problem with providing a 3-core cable and connecting up the earth conductor. And after all if 2 levels of protection is good, 3 levels is better. Option 1 is obviously to stick with the design as is and educate sales/customers where necessary. If you provide the product with a moulded-on mains plug, they'll never know it's Class 2 unless they read the rating label! Are you sure that the capacitance between the internals and the metal case is low enough for there to be no detectable 'touch current' if someone touches earth with one hand and your box with the other? Such a detectable current is not hazardous but is extremely aversive - people won't like working with the product if it 'bites', even gently. Assume that all the internals are at half mains voltage to true earth, i.e. 115 V in UK. Now you need to get the touch current down to 0.5 mA at most, preferably 0.3 mA. 115 V and 0.3 mA means 8.3 nF maximum capacitance. Possible, with care. Will your SMPS meet the conducted emission limits with no earth connection? Option 2 is to provide a 3core product for the some markets and a 2core product for others. This goes against the original intention to have a universal product. Yes. not convenient at all. Is there an option 3? ie provide 3core cable and explain in the manual that product is designed to be safe without an earth but the earth may be fitted if desired. What about the square in square symbol? If you provide a 3-core cable, you MUST NOT refer to the product as 'Class 2' or put the double-square symbol on it. But you can explain in the instructions book, if you want to. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- 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: Metrics cost at 1991
I read in !emc-pstc that oover...@lexmark.com wrote (in 200111051625.LA a06...@interlock2.lexmark.com) about 'Metrics cost at 1991', on Mon, 5 Nov 2001: I cannot confirm the following statement but I have attached a link identifying the actual event. Here, supposedly, is a quote from a Petrobras executive extolling the benefits of cutting QA and inspection cost on the drilling/production platform project that sunk into the Atlantic Ocean off the coast of Brazil in March of 2001. Well, he presumably reaped the reward of 'going too far'. Such failures DO NOT mean that cost reduction, re-appraisals of requirements and the elimination of unnecessary regulation are bad in themselves, but they must not be carried to excess. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- 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: Metrics cost at 1991
I read in !emc-pstc that Ehler, Kyle keh...@lsil.com wrote (in 95fbd8b0830ed511b7720002a51363f102905...@exw-ks.ks.lsil.com) about 'Metrics cost at 1991', on Mon, 5 Nov 2001: Naturally, the project dictated to me is to attempt an analysis of the EMC compliance process used here. This will be an attempt to apply structured analysis procedures in efforts to better understand and apply changes in personnel and/or test/scheduling procedures to shorten cycle time and perhaps reduce costs. We seem to spend 15% of lab resources in actual compliance work and 85% in troubleshooting to get compliant. I get the impression that your company is not training its design engineers to think of EMC (and safety) right up front at the design stage. Or maybe it tells them to do that but doesn't train them in how to do it. NO way should you be troubleshooting to the extent you quote. My audio design team were told that THEY were responsible for their product's safety; they could discuss freely with the compliance team in advance of submitting the product for test, and they had free access to the safety standard, BUT the product MUST NOT FAIL at first submission. It worked very well, except on one product, where we had one unit (out of about 200 000 product units that we shipped) with a screw through the mains lead - a hazard that everyone had missed. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- 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.
Safety Critical etc - the future - Are we professionals? Milestones not Millstones.
I read in !emc-pstc that Gregg Kervill gkerv...@eu-link.com wrote (in 003301c16614$de9ced90$7300a8c0@MENHADEN) about 'Safety Critical etc - the future - Are we professionals? Milestones not Millstones.', on Mon, 5 Nov 2001: Good Morning John, and how are you today? OK, up to now, thank you. Many thanks for your answer - I could not have hoped for a better illustration of what happens when a reader does not understand the background behind, the intent or the values of the person (or the committee) doing the writing, and then gets it totally wrong. And heaven knows I've done that often enough myself! Don't be too sure that I do not understand what you wrote. Of course, what you meant might be something other and not discernible. [snip] Whilst we all rely heavily upon IEC and other standards - what I tried to explain was that these standards are not revolutionary but evolutionary. This is not a universal rule, but is a guiding principle. Working in 'geological time' is not only a good time - it is ESSENTIAL for business. (If they were reactive industry would never keep up with the changes and we would be constantly re-certifying products.) No, that is not true. Industry is constantly pressing IEC to speed up its processes; that is why we now have new types of IEC documents - PAS, TS. The important matter of avoiding the need for re-certification is dealt with at the *regulatory* level - not in IEC at all - by the 'dow' timing rules, such as those adopted by the European Commission in conjunction with CEN, CENELEC and ETSI. What this means is that compliance engineers will face situations that do not appear in the standards. This is being dealt with - rather haphazardly, it appears to me and I am taking that point up whenever possible - by the issue of official 'interpretations', which may clarify wording that proves to need it or may specify how the standard applies in circumstances, such as new technological developments, that were not envisaged when the standard was written. Interpretations are not a new concept, but in the past they were produced by bodies other than the relevant standards committee and were not widely circulated. It means that compliance engineers will be face the day-to-day need to make up compliance criteria On-the-hoof; almost invariably under extreme pressure because we are 'responsible' for holding up the job, payment and shipment. Interpretations, widely circulated, should eliminate this. Note that *anyone*, as far as IEC is concerned, can ask for, or propose, an interpretation, but some National Committees make it next to impossible for their people to do so. The result is that the sum-total of custom and practice will flow down (via engineers such are yourself) and find its way into TC's and Standards. Hence things - and attitudes - will change. (For example - a few years ago you bitterly opposed my call for double mains fusing - yet I have seen more recent correspondence, from you, that proposed double mains fusing.) Things change. I certainly challenged you statements about it, because: - it's not mentioned at all in IEC60065 and only obscurely in IEC60950 (editions valid at that time); - it isn't necessary in UK because we don't have reversible mains plugs; - I didn't realise that the Schuko plug is reversible. When you responded and I found out about the Schuko, I accepted your argument. That's how standards committees work. Hence compliance engineers need the framework provided by standards but will be expected to work outside that framework. Again, not too far, I hope. In this meeting space we have had a broad input of specific needs (for the nuts and bolts, I have received private correspondence that I was asked to address in public - as my last email. BUT, what I was attempting was to stimulate the discussion to include how we establish the scope - content - education - interpersonal and other skills needed by compliance engineers. You did that! As compliance engineers we are free thinkers - how do me ensure and encourage that free thinking - how do we ensure that we can draw upon each others experiences (being ever conscious that many of us are consultants and cannot afford to become a free source of information to potential clients). Well, I used to get uptight about free-loaders - people who phoned to pick my brains without paying. But that anger didn't affect them, it just distracted me. So now I run a LIMITED free advice service, and I say when it stops being free! So how do we go ahead? I believe that we must continue to provide inputs for standard development. This will allowing standards to become landmarks that mark our progress: and not become millstones that hold us back. (No insult intended - quite the opposite in fact. There are some that take a view that if a hazard is not in covered by the standard they do not NEED to consider it. We know that is not the INTENT of the standard, as I listed in my last email).
RE: Safety Critical etc - the future
Let's give it a try Safety Critical Components : Those components that encapsulate into one single component the 2 safety layers that are normally used to isolate the operator (and others) from a hazard. In electrical safety land that's mostly an electrical hazard Safety Related Component All components that -by there function- may create a hazardous situation when defective, direct or indirect. All safety critical components are safety related; the inverse is not necessary true. As you may all know, most protection systems in safety land consist of 2 layers. A well known concept is double insulation. Both layers of a double insulation are in themselves not a safety critical component; once they are integrated into one part -called reinforced- they are. Both insulation layers are only safety related components. They have to meet their specs; if one layer fails nothing happens. If they do not meet their specs you have a problem. That's why they are safety related. A supply transformer of a not grounded SELV is a safety critical component. A supply transformer of a grounded SELV is a safety related component. The insulation sheets (if double) are safety related each. The latter creates (when defective) a hazard only when the grounding fails. I believe that similar reasoning can be made for most hazards, although most safety related standards are not implementing this in full. Fa. a hot component needs protection for the operator in 2 ways: (1)limited access + (2) warning Both protection methods are safety related. If they are integrated in ONE, or if one measure is not possible, the other becomes safety critical. Fire protection: 2 measures: (1) limit the temperature of component + (2) no combustible materials close to it If you are not allowed to remove dangerous and flammable objects far away from a heat generating component, then the temperature limiter becomes critical. To make the measures non critical another degree of protection is required. This is called redundancy. ( in fact the second layer is redundant too, but seen from the safety perspective two layers is a minimum) Creating a safe device has everything to do with creating multiple layers of safety. Letting your PC control a Hazardous process is an often made mistake against this rule. Not only is software error-sensitive (and difficult to debug), but the hardware most often is crash vulnerable. One crash would create a hazardous situation. Hardened Personal computers will limit this risk, as does certified software, but for true safe operation on the level we are used to work with in f.a. insulations, you would need 2 computers in parallel, plus a decision device, of which the operation will then be safety critical. The safety standard EN 60730 (that I am a bit familiar with) shows many ways of creating dual safety concepts for processor controlled hazardous processes. The single fault concept we are familiar with is just a way of finding out all just safety related components and -measures, so we can finally identify the safety critical ones and take precautions. Many standards have pre-cooked these concept in lists of simple measures, more easy to use in checklist form. This does not mean we should limit ourselves to these checklists. The art of safety thinking is finding and recognizing these double protection layers in equipment, processes and concepts (or the lack thereof). And most important: not forgetting one. 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 Allen, John Sent: Friday, November 02, 2001 9:52 AM To: 'Rich Nute'; lcr...@tuvam.com; emc-p...@ieee.org Subject: Safety Critical etc - the future Hi Folks We have now had this discussion and it brought out a number of useful and enlightening points, and Lauren's and Rich's summaries of the various inputs are both interesting and thought-provoking. However, I now come back to a point that I made in one of my earlier messages: Where do we go from here? For most people participating in this forum, I suspect that the major contact that they have with any concept of component- criticality is in respect of simple standards (e.g. standards mandated under the LVD/EMC/RTTE or other national equivalents) compliance for a single item of equipment. Their major issue will, I guess, be the attitudes taken by the various product test and certification authorities that they deal with because those organisations directly influence what the product design and manufacturing companies need to reflect in their internal documentation and processes. Therefore, the test and certification authorities need to
Re: EMC test table construction plans
I read in !emc-pstc that Michael Taylor mtay...@hach.com wrote (in 7798e57399e3d211b11600902762695205c15...@lvexch1.lvl.hach.com) about 'EMC test table construction plans', on Mon, 5 Nov 2001: We successfully used these woods in stands that were subjected to charge deposition in excess of 6000 micro Coulombs That doesn't sound very big. and direct lightning strikes of 10.7MV without breakdown. Of course the appropriate design constraints were followed for stress equalization and gradient control. As a general rule (if the wood is properly specified and moisture controlled) a value of 0.76 of Teflon can be used for calculation of properties. Value for what? Cost? (;-) -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co..uk Eat mink and be dreary! --- 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: Metrics cost at 1991
I once worked for a Quality manger who insisted that everyone wrote using a black ball point pen. He was the exception (using pencil) When I challenged him we replied So I can rub out my mistakes. God please him... The main advantage of the note book over PDA and laptops are: They show who wrote the entries (handwriting) They do not break when you drop them G Keeping a lab notebook was one of the first ideas that they taught us in college laboratory courses; I thought it was a pain in the $%#@** back then. But, whenever anyone asks me how long it took us to test a product, how much time we spend troubleshooting (which is always followed by the question of how long it will take for the next one); I find these notebooks to be worth their weight in Gold. Of course, for you electronics lovers out there, a laptop, palm pilot... would possibly work. I don't use them because I find them restrictive. When I'm in the lab, I need to draw block diagrams, to make sketches, to take notes. I really haven't found a hardware/software combination in a laptop or palmtop that works as quickly or as well as good old pencil CAD. attachment: winmail.dat
Re: CLASS 11(DOUBLE INSULATED) 2/3-CORE CABLE
A word of history on Class I vs. Class II, as I understand it. In the beginning there was no such thing as earth grounding in homes and offices for the needed electrical appliances. The equivalent of our present double insulation was required to prevent against electric shock. When structures began to include earth grounded outlets, this method of protection required only basic insulation, i.e. cheaper for the average appliance cost of materials, hence a rapid use of Class I designs. However, given what I know about each, I prefer Class II devices for home appliances and tools, as there is no dependence on the ground path, which may be compromised in the device, the cord, extension cords, house wiring, and so on. Just my personal opinion. George Alspaugh --- 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: CLASS 11(DOUBLE INSULATED) 2/3-CORE CABLE
Several years ago I had the need to explain this same issue. Similarly most of the inquiries came from the U.K. Here are some exerpts from a white paper done to address this issue: *** This document addresses the nature and safety of two-wire ITE products. The international safety standard for ITE is IEC 60950. The referenced sections of IEC 60950 below are generally the same in unique country standards. SHOCK PROTECTION A major aspect of product safety for ITE is protection against electric shock. There are three equally acceptable methods of achieving this protection (section 1.2.4). Class I equipment employs only basic insulation, but ties all accessible conductive parts to a ground pin to protect the user in the event of a failure of the basic insulation. Such equipment requires a three-wire line cord and a reliable path to earth ground. Class II equipment uses double or reinforced insulation between primary voltage and accessible conductive parts to protect against electric shock. Such equipment uses a two-wire line cord, is not dependent on the integrity of the building's grounding system, and typically displays the square within a square symbol denoting double insulation. ITE products which contain no hazardous voltages (e.g. less than 42.4Vpk/60Vdc) are approved as Class III devices. NATURE OF CLASS II There is one aspect of Class II equipment that can confuse end users. Because no earth ground path is required or available, accessible conductive parts will float to some voltage less than the applied mains voltage. Typically this may be one-half of the mains voltage. This voltage is not considered a hazard under the standards as the available current cannot exceed the 250uA specified in Table 17 of section 5.2.2. Some individuals may be able to feel a slight tingle or shock at this low current level, although no electric shock injury should result. FINAL COMMENTS If a user is aware of a voltage on an accessible part, and suspects a hazardous condition, some simple tests can be performed to eliminate this concern. George Alspaugh --- 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: CLASS 11(DOUBLE INSULATED) 2/3-CORE CABLE
At home my video recorder, hi-fi and Satellite box, have metal outer enclosure. But are supplied by a two pin IEC320 C8 connector, running back to a UK three pin plug. The earth core is simply not present in the power cord. Products are marked with the Square within a Square and the manuals state they are double insulated, not reliant on a protective earth. So your option three and pretty standard practice for such domestic goods. If you decide to run an earth to the chassis, or follow the product may be earthed if so desired route. Then I advise you look in EN60950 sec 2.6.2 for the requirements on Functional Earthing to ensure you are still meeting all the spacing and insulation requirements for a double insulation and SELV circuits. As usual my opinion, not that of my employers. Andrew Wood wrote: All I have a piece of equipment falling under the scope of EN6010. To set the scene it is a low volume product, approx 0.5m cube, stainless steel enclosure and will sit on a bench in food cold storage areas. Mains lead connects via IP68 connector. It incorporates a SMPS for universal mains operation ( current draw approx 0.3A). Because of problems ensuring a reliable earth in some locations for its predecessor, I have specifically designed it to be Class2 (double insulated). Therefore safe for all markets. Now, ironically, I am encountering some unease with the UK sales dept. After all everyone KNOWS that a metal box should be earthed. (I don't dismiss this attitude lightly because it is no doubt shared by some of the customer base.) Technically there is no problem with providing a 3-core cable and connecting up the earth conductor. And after all if 2 levels of protection is good, 3 levels is better. Option 1 is obviously to stick with the design as is and educate sales/customers where necessary. Option 2 is to provide a 3core product for the some markets and a 2core product for others. This goes against the original intention to have a universal product. Is there an option 3? ie provide 3core cable and explain in the manual that product is designed to be safe without an earth but the earth may be fitted if desired. What about the square in square symbol? I'm sure that I'm not the first to be looking at these questions. Any and all thoughts would be appreciated. Best regards, Andy. Andrew Wood Engineer (Specials) Land Instruments International England Please excuse following message automatically inserted by server This e-mail and its contents may be confidential, privileged and protected by law. Access is only authorised by the intended recipient. The contents of this e-mail may not be disclosed to, or used by, anyone other than the intended recipient, or stored or copied in any medium. If you are not the intended recipient, please advise the sender immediately. --- 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. -- Andrew Carson - Product Safety Engineer, Xyratex, UK Phone: +44 (0)23 9249 6855 Fax: +44 (0)23 9249 6014 --- 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: Safety Critical etc - the future
There are a few of us lurking in the background -- I'm on the US TAG for SC77A and SC77B (Immunity) as well as convenor of SC77B WG11 and member of WG9 and SC77A WG6. I'm constantly looking for industry input to the immunity standards and will present whatever information I receive, but that doesn't mean anything will happen -- quickly, slowly or at all. The WG's and TAG's I'm involved with are represented by a broad cross section of industry -- TAG's being US; WG's being international -- and many decisions become compromises in one way or another. Even if a WG KNOWS how to improve a standard technically, if it is going to involve companies buying new testers or modifying existing ones to meet the new requirements, the chances of getting published get much smaller.. Of the groups I'm part of -- for example WG11 -- only two members are independent test facilities. Others are industry -- Siemens, Philips, Nokia, IBM, Sun, HP, Schneider, Tele Danmark, Allen Bradley, Tokin, etc... Some of these experts run labs within their companies, but they are not NRTL's or Competent Bodies. This composition is similar in the other WG's I'm familiar with, as well as the US TAG's... Mike Hopkins Thermo KeyTek -Original Message- From: Scott Barrows [mailto:sbarr...@curtis-straus.com] Sent: Friday, November 02, 2001 2:18 PM To: geor...@lexmark.com Cc: emc-p...@ieee.org; Allen, John Subject: Re: Safety Critical etc - the future Hi All, With the remarks about this topic needing to be discussed in IEC and industry committees as well as between professionals, I think it may be time to inject that there are local Product Safety Societies (or the IEEE versions) that were formed for this particular reason. Perhaps the Engineers that sit on these TAG and TC committees should join up and take an ACTIVE role in these groups. With their participation in local safety societies, the entire industry will be represented and can be considered to have a voice in the development of standards and the considerations therein. I am not so sure that the NRTL's and Notified bodies should have the only voice in this process. Scott Barrows NPSS geor...@lexmark.com wrote: John, Allow me to comment further on this issue. I seem to remember a saying that goes The proof of the pudding is in the eating. By the same token, I have always expressed within my area of influence that the truest test of our internal ITE safety policies, practices and processes is field history. We all know that standards, like many other sets of knowledge, evolve from errors over time. Another saying that makes this point is Success comes from experience. Experience comes from failure. Overall, I believe the ITE industry has a superb safety record, given the exponential growth of this industry from corporate uses to homes, dorm rooms, etc. Hundreds of people are killed or injured every day in the use of various products, e.g. vehicles, farm equipment, firearms (hunting accidents), aircraft, etc. The majority of these are due to operator error and/or poor judgement. The more complex products are the ones more likely to develop a defect that could lead to deaths, e.g. aircraft. In the eight plus years I have been in product safety, I am not aware of a reported serious injury or death from the intended use or misuse of an ITE product. This does not mean there have been none, but it does mean that ITE is not a significant cause of injury or death. This is a result of fairly sound standards, common sense, experience, and due diligence in maintaining the original certified design of each product. We probably all know of improvements we would make in this process if we got to be king for a day. Most of us handle these as internal requirements beyond the imposed external requirements. The way we define and account for the use of safety critical parts is one small aspect of a much more complex series of processes leading to protecting ITE users from harm. George Alspaugh These are personal opinions only. --- 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
Seeking Conformal Coating Service USA/EU
All, I'm looking for recommended vendors (or warnings of bad vendors) with UL approved coating process for circuit boards to meet the requirements of hazloc or classified locations. I need vendor(s) that can support manufacturing operations in Texas/USA and Hungary/EU. Thanks in advance! Best Regards, Eric Lifsey Compliance Manager National Instruments --- 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: Metrics cost at 1991
I have a simple idea to add to this, I'll make the point by analogy. I listened to a book on tape one time. The book was by an author who wrote about investing, saving and other financial strategies. He looked at the habits of financially successful people and tried to find trends. OK OK, I'm getting to it. One trend that he found is that financially successful people don't spend too much time trying to budget and predict how much money they were going to spend. But they did keep good records of how much they spent, what they spent it for and where they spent it. This knowledge allows them to budget almost as second nature, they already know how much they spend and for what. Also, if they stay in the black they already have an idea of how much they can spend. What's the point. A good prediction system and any efforts to fix, cost reduce and/or speed up the compliance process needs to start with good record keeping. May I suggest a good old paper notebook. Every time I go into our compliance room here at the factory, or go with a product to the test lab, I am armed with this notebook. Everyday I use it, I put the date and project at the top of the page. I then use it to record all sorts of notes...pass/fail, troubleshooting, we tried this, we tried that... I keep this notebooks labelled in my office. I then refer to them in my neat word processed compliance reports. Keeping a lab notebook was one of the first ideas that they taught us in college laboratory courses; I thought it was a pain in the $%#@** back then. But, whenever anyone asks me how long it took us to test a product, how much time we spend troubleshooting (which is always followed by the question of how long it will take for the next one); I find these notebooks to be worth their weight in Gold. Of course, for you electronics lovers out there, a laptop, palm pilot... would possibly work. I don't use them because I find them restrictive. When I'm in the lab, I need to draw block diagrams, to make sketches, to take notes. I really haven't found a hardware/software combination in a laptop or palmtop that works as quickly or as well as good old pencil CAD. Stay compliant guys Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | .. -Original Message- From: Ehler, Kyle [SMTP:keh...@lsil.com] Sent: Monday, November 05, 2001 9:31 AM To: wo...@sensormatic.com; 'EMC and Safety list' Subject: RE: Metrics cost at 1991 Richard, et al This sounds like a Six Sigma project. Having just completed my 'green belt' training, I have been assigned a project to complete my certification as a Six Sigma green (horn) belt. This is a *huge* undertaking for me.. Naturally, the project dictated to me is to attempt an analysis of the EMC compliance process used here. This will be an attempt to apply structured analysis procedures in efforts to better understand and apply changes in personnel and/or test/scheduling procedures to shorten cycle time and perhaps reduce costs. We seem to spend 15% of lab resources in actual compliance work and 85% in troubleshooting to get compliant. Accuracy in resource scheduling has proven to be as easy as nailing jelly to a tree.. I saw your list and immediatly recognized its similarity to mine. This work starts and ends with confounding metrics. From your list I see that you have 'Defects Per Unit' (DPU), but nothing about Opportunities For Error (OFE) that occurs with gaining compliance for new products. I think this would be the key to unraveling the mystery. I see that you apply DPU as EMC failures, but I was thinking of DPU as failures in meeting schedule. Is this too weird? Any thoughts on how to calculate OFE on a new product that is bound to be rife with opportunities due to the use of latest technology such as for example, 2+ Gbps fibre channel and its accomodating -new- mechanical packaging? For your engineering types, the concept of determining opportunities for compliance failure may be alien to them. It is for ours. I am skeptical that these guys could tell me anything meaningful until they get their training. -but I keep an open mind. On major item I picked up in my SS training was the myriad of ways the metrics can be charted and considered. Best Regards, Kyle Ehler KCØIQE mailto:kyle.eh...@lsil.com Assistant Design Engineer LSI Logic Storage Systems Div. 3718 N. Rock Road U.S.A. Wichita, Kansas 67226 Ph. 316 636 8657 Fax 316 636 8321 -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of wo...@sensormatic.com Sent: Thursday, November 01, 2001 3:20 PM To: emc-p...@majordomo.ieee.org Subject: Metrics My management is asking each
RE: CLASS 11(DOUBLE INSULATED) 2/3-CORE CABLE
Andrew Don't try to explain that double insulation and earthing are both acceptable alternatives - only 1 persion in 10 will understand and the public won't care! Option 1 - I think knowledgeable technical people in most countries would actually prefer this for the reasons you mention in your 2nd paragraph - but there are very few of these technical people. Option 2 - Messy open to continued confusion for everybody - including your own staff. Option 3 - Provided there is double insulation between the hazardous parts and the metal case, remove the double-insulation mark )not allowed on a Class II product) and provide installation instructions as for a normal earthed product (i.e. MUST be earthed). Then if someone does not earth it the product should still be safe. (This is the way Rich Nute often explains the use of double-insulation in many of HP's earthed products.) My preference is Option 3 - almost the least effort and probably the least customer and marketing hostile reactions (but it will cost a little more for the cable and strain relief). # Additionally it might (or might not?) help with any static control problems - which can get quite nasty in cold areas where the humidity is very low - and with any equipotentialisation problems which could occur because cold-stores are metal walled. Regards John Allen -Original Message- From: Andrew Wood [mailto:andrew.w...@landinst.com] Sent: 05 November 2001 14:27 To: 'emc-pstc' Subject: CLASS 11(DOUBLE INSULATED) 2/3-CORE CABLE All I have a piece of equipment falling under the scope of EN6010. To set the scene it is a low volume product, approx 0.5m cube, stainless steel enclosure and will sit on a bench in food cold storage areas. Mains lead connects via IP68 connector. It incorporates a SMPS for universal mains operation ( current draw approx 0.3A). Because of problems ensuring a reliable earth in some locations for its predecessor, I have specifically designed it to be Class2 (double insulated). Therefore safe for all markets. Now, ironically, I am encountering some unease with the UK sales dept. After all everyone KNOWS that a metal box should be earthed. (I don't dismiss this attitude lightly because it is no doubt shared by some of the customer base.) Technically there is no problem with providing a 3-core cable and connecting up the earth conductor. And after all if 2 levels of protection is good, 3 levels is better. Option 1 is obviously to stick with the design as is and educate sales/customers where necessary. Option 2 is to provide a 3core product for the some markets and a 2core product for others. This goes against the original intention to have a universal product. Is there an option 3? ie provide 3core cable and explain in the manual that product is designed to be safe without an earth but the earth may be fitted if desired. What about the square in square symbol? I'm sure that I'm not the first to be looking at these questions. Any and all thoughts would be appreciated. Best regards, Andy. Andrew Wood Engineer (Specials) Land Instruments International England Please excuse following message automatically inserted by server This e-mail and its contents may be confidential, privileged and protected by law. Access is only authorised by the intended recipient. The contents of this e-mail may not be disclosed to, or used by, anyone other than the intended recipient, or stored or copied in any medium. If you are not the intended recipient, please advise the sender immediately. --- 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: 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
RE: EMC test table construction plans
Some time ago, in a galaxy far far away at the Rocket Ranch - - - I was involved in a study to determine the dielectric breakdown mechanisms in Solid Rocket Propellant. It was necessary to construct a large number of stands or Platforms to hold large blocks of propellant. These blocks were subjected to a variety of charging methods as well as simulated Lightning. As you can surmise these stands were used only ONCE. Because we were consuming these Stands at a high rate we were forced to go to less expensive construction material. Wood was the best 2nd choice. We initiated a detailed study of the dielectric characteristics of various wood types. We found after extensive study that the conductivity of the wood is controlled by both the moisture content (big surprise) and the level of organic salts minerals contained in the growth ring boundary. We found that the best wood from an insulation standpoint was Balsa. However this wood had no structural strength. The next best was white Poplar or Ash, Triple kiln dried with 2-3 coats of marine varnish. We successfully used these woods in stands that were subjected to charge deposition in excess of 6000 micro Coulombs and direct lightning strikes of 10.7MV without breakdown. Of course the appropriate design constraints were followed for stress equalization and gradient control. As a general rule (if the wood is properly specified and moisture controlled) a value of 0.76 of Teflon can be used for calculation of properties. For what it's worth. Michael Taylor Awaiting winter in Colorado -Original Message- From: Scott Lacey [mailto:sco...@world.std.com] Sent: Friday, November 02, 2001 5:04 PM To: POWELL, DOUG Cc: emc-p...@majordomo.ieee.org Subject: RE: EMC test table construction plans Doug, Wood is ok if you seal it properly to prevent absorbed moisture from causing inconsistancies from one test to the next. Most clear resins do not cause RF problems whereas the metallic pigments in paints often do. If you can, covering the top with laminate (Formica) increases durability and provides a low friction surface. The best design is to make a sturdy table using the following criteria: 4 X 4 or doubled 2 X 4 legs. Top of 2 layers of 3/4 plywood or particle board. Apron to support legs of at least 2 X 4 or 3/4 X 6 cross section. Pivoting top overlay of 3/4 plywood or particle board with a piece of 1 1/2 PVC pipe for a pivot. What you do is either cover the table surfaces (top bottom) with laminate or sand, seal (multiple coats) and sand again plus wax to allow easy rotation. Drill matching holes through the center of the 3/4 overlay and the tabletop for the stub (4 long or so) of pipe. glue the pipe flush with the top of the overlay (it will protrude from the bottom). You just drop the overlay with pipe onto/into the tabletop with hole. During testing the table is rotated (1/4 turn) manually between tests. If you doubt that laminate can provide a low friction bearing, try this test - turn one table upside down on top of an identical table, rotate the top table, and then try rotating the table with a coworker standing on it. If you find too much friction apply some automotive paste wax. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of POWELL, DOUG Sent: Thursday, November 01, 2001 12:38 PM To: EMC-PSTC (E-mail) Subject: EMC test table construction plans Hello all, I plan to construct my own insulated EMC test table for a 5 meter chamber. Seems simple enough to do and I could easily come up with something. I thought I might first ask for input from those of you in the discussion group who have experience or maybe even construction plans. Here are some features I want: 1) I will be testing products that weight up to 200 Lbs (91 kg). 2) I want to minimize metalic fastners. 3) I would like to make it a pivoting table (not motorized). 4) Height is 80 cm. 5) The surface should be replacable if it gets badly worn or scarred. I'm thinking of using hardboard. 6) Suggestions on length width? -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- 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:
RE: Metrics cost at 1991
I cannot confirm the following statement but I have attached a link identifying the actual event. Here, supposedly, is a quote from a Petrobras executive extolling the benefits of cutting QA and inspection cost on the drilling/production platform project that sunk into the Atlantic Ocean off the coast of Brazil in March of 2001. Petrobras has established new global benchmarks for the generation of exceptionally shareholder wealth through an aggressive and innovative programme of cost cutting on it's P36 production facility. Conventional constraints have been successfully challenged and replaced with new paradigms appropriate to the globalised corporate marketplace. Through an integrated network of facilitated workshops, the project successfully rejected the established constricting and negative influences of prescriptive engineering, onerous quality requirements, and outdated concepts of inspection and client control. Elimination of these unnecessary straightjackets has empowered the project's suppliers and contractors to propose highly economical solutions, with he win-win bonus of enhanced profitability margins for themselves. The P36 platform shows the shape of things to come in an unregulated global market economy of the 21st Century. Articles related to the sinking. http://www.cnn.com/2001/WORLD/americas/03/20/brazil.rig.03/index.html http://www.offshore-technology.com/projects/roncador/ http://www.findarticles.com/cf_0/m0BEK/7_9/76937714/p1/article.jhtml?term=petrobras+p-36 * Opinions and statements made are mine and mine alone and do not reflect those of my employer. Gregg Kervill gkervill%eu-link@interlock.lexmark.com on 11/02/2001 04:58:59 PM Please respond to Gregg Kervill gkervill%eu-link@interlock.lexmark.com To: woods%sensormatic@interlock.lexmark.com, emc-pstc%majordomo.ieee@interlock.lexmark.com cc:(bcc: Oscar Overton/Lex/Lexmark) Subject: RE: Metrics cost at 1991 Sorry about the HTML but this is an abstract from the book The Practical Guide to the Low Voltage Directive ISBN 0 7506 3745 5 Metrics come in all sizes - what does your management want to hear? How much we spend - how could have been save with better project management and design control - how much compliance cost? How much RD spend - How much compliance costs? (I believe that DELL commit 30% of RD to compliance) I wonder why? I wonder if their competitors would advertise the fact that We commit MUCH less than that - so buy our products. Does sell to me!!! But I have been called cynical by more that two people. LOOK at history for the TRUE cost of getting it wrong. These - hopefully explain the TRUE cost of 'keeping it right' and not just consider the cost of adding a few extra scraps of metal or fuses. Titanic ( faulty material) Challenger (Faulty gasket) Meteosat (the one with the dead French PSU that should have driven the down-link Tx) Herald of Free Enterprise (faulty 'safety' switch and operator error - drunk and asleep) GoodYear Tyres (jury still out) The problem with compliance is that the TANGIBLE COST is always evident - it is only when there is non-compliance that the intangible benefits become self evident. Please not the following abstract and the graphs. PLEASE remember that the cost indicated here are from 1991 data. However - if we are looking at OVERALL costs think also of a few of the high profile examples. COPYRIGHT Butterworth-Heinemann andGregg Kervill The Limitations of the guidance notes In addition to a detailed step by step guide to electrical safety, this book contains an Easy Guide. This provides simple, easy to follow steps that will result in a compliant product, at the same time reducing design effort, and simplifying safety compliance testing. The strength of these guidance notes is that they reduce development time and design changes, because by following the guidance it will remove many opportunities for designing a non-compliant product. The penalty for using only the Easy Guide may be that the unit cost is higher than a similar product designed following the Detailed Guidance notes. The Easy Guide is therefore particularly suited to the design of one-off equipment and low volume products Conversely, the Detailed Guidance Notes will be required for high volume, low margin products. They describe all aspects of the standard in depth allowing the designer to take advantage of low cost design options to minimise the unit cost of the final product. The penalty for using this approach is that greater knowledge of the standard and its interpretation is required and the cost of safety compliance verification can be significantly higher. Reducing costs and time to market It is surprising how few people appreciate that most of the whole life costs of a product are fixed early on during the initial design phase. The adjacent diagrams show the relative costs that can be set in stone even before
RE: Safety Critical etc - the future - Are we professionals? Milestones not Millstones.
Good Morning John, and how are you today? Many thanks for your answer - I could not have hoped for a better illustration of what happens when a reader does not understand the background behind, the intent or the values of the person (or the committee) doing the writing, and then gets it totally wrong. And heaven knows I've done that often enough myself! I feel passionate about the regulatory work - I am committed to education (I sit on the IEEE Education Committee), I have lectured world-wide (not just in the UK and US) and am about to put a dozen training courses on-line. I believe that as compliance professionals we share (collectively and as individuals) enormous responsibility within our chosen profession. (As a design engineer I felt far less personal exposure for design decisions that I made then than I feel now in compliance engineering.) Whilst we all rely heavily upon IEC and other standards - what I tried to explain was that these standards are not revolutionary but evolutionary. Working in 'geological time' is not only a good time - it is ESSENTIAL for business. (If they were reactive industry would never keep up with the changes and we would be constantly re-certifying products.) What this means is that compliance engineers will face situations that do not appear in the standards. It means that compliance engineers will be face the day-to-day need to make up compliance criteria On-the-hoof; almost invariably under extreme pressure because we are 'responsible' for holding up the job, payment and shipment. The result is that the sum-total of custom and practice will flow down (via engineers such are yourself) and find its way into TC's and Standards. Hence things - and attitudes - will change. (For example - a few years ago you bitterly opposed my call for double mains fusing - yet I have seen more recent correspondence, from you, that proposed double mains fusing.) Things change. Hence compliance engineers need the framework provided by standards but will be expected to work outside that framework. In this meeting space we have had a broad input of specific needs (for the nuts and bolts, I have received private correspondence that I was asked to address in public - as my last email. BUT, what I was attempting was to stimulate the discussion to include how we establish the scope - content - education - interpersonal and other skills needed by compliance engineers. As compliance engineers we are free thinkers - how do me ensure and encourage that free thinking - how do we ensure that we can draw upon each others experiences (being ever conscious that many of us are consultants and cannot afford to become a free source of information to potential clients). So how do we go ahead? I believe that we must continue to provide inputs for standard development. This will allowing standards to become landmarks that mark our progress: and not become millstones that hold us back. (No insult intended - quite the opposite in fact. There are some that take a view that if a hazard is not in covered by the standard they do not NEED to consider it. We know that is not the INTENT of the standard, as I listed in my last email). Suggested path forward: From established compliance engineers I want to know what helped you to develop in your career. From those developing and developing other - what tools do you need From everyone - where we go from here.. Hopefully the message is a little clearer this time - sorry to all who I confused. Best regards Gregg --- 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: European Hydraulic Control Valve Requrierments
Peter, I think this refers to annex II of the Machinery Directive, which defines the format for the required Declaration of Conformity. Rather than go into depth here, I suggest you take a look at the full text of the Directive (it's on the Europa server) and it should then make sense. I would not normally expect hydraulic control valves to be within the scope of the PED since they will generally be covered by the exclusion within the PED which permits it to be disapplied for apparatus which are in the lower risk categories and are also covered by the LVD or machinery directives, at least one of which probably will apply to the valves. Regards Nick. At 11:37 +0200 1/11/2001, Peter Merguerian wrote: Dear All, Anyone one knows what CE-IIA or CE-IIB mean? I assume Class IIA or Class IIB. Is this from the Pressure Equipment Directive? The product in question is an automatic hydraulic control valve. Regards, This e-mail message may contain privileged or confidential information. If you are not the intended recipient, you may not disclose, use, disseminate, distribute, copy or rely upon this message or attachment in any way. If you received this e-mail message in error, please return by forwarding the message and its attachments to the sender. PETER S. MERGUERIAN Technical Director I.T.L. (Product Testing) Ltd. WARNING: The remainder of this 4K message has not been transferred. Turn on the Fetch button in the icon bar and check mail again to get the whole thing. --- 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: Metrics cost at 1991
Richard, et al This sounds like a Six Sigma project. Having just completed my 'green belt' training, I have been assigned a project to complete my certification as a Six Sigma green (horn) belt. This is a *huge* undertaking for me.. Naturally, the project dictated to me is to attempt an analysis of the EMC compliance process used here. This will be an attempt to apply structured analysis procedures in efforts to better understand and apply changes in personnel and/or test/scheduling procedures to shorten cycle time and perhaps reduce costs. We seem to spend 15% of lab resources in actual compliance work and 85% in troubleshooting to get compliant. Accuracy in resource scheduling has proven to be as easy as nailing jelly to a tree.. I saw your list and immediatly recognized its similarity to mine. This work starts and ends with confounding metrics. From your list I see that you have 'Defects Per Unit' (DPU), but nothing about Opportunities For Error (OFE) that occurs with gaining compliance for new products. I think this would be the key to unraveling the mystery. I see that you apply DPU as EMC failures, but I was thinking of DPU as failures in meeting schedule. Is this too weird? Any thoughts on how to calculate OFE on a new product that is bound to be rife with opportunities due to the use of latest technology such as for example, 2+ Gbps fibre channel and its accomodating -new- mechanical packaging? For your engineering types, the concept of determining opportunities for compliance failure may be alien to them. It is for ours. I am skeptical that these guys could tell me anything meaningful until they get their training. -but I keep an open mind. On major item I picked up in my SS training was the myriad of ways the metrics can be charted and considered. Best Regards, Kyle Ehler KCØIQE mailto:kyle.eh...@lsil.com Assistant Design Engineer LSI Logic Storage Systems Div. 3718 N. Rock Road U.S.A. Wichita, Kansas 67226 Ph. 316 636 8657 Fax 316 636 8321 -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of wo...@sensormatic.com Sent: Thursday, November 01, 2001 3:20 PM To: emc-p...@majordomo.ieee.org Subject: Metrics My management is asking each engineering group to devise and apply metrics to our department operations. I have struggled for a couple of years to devise meaningful metrics as applied to EMC and product safety compliance testing and certification , but with little success. Some ideas have been: * % of received products that are found to be fully compliant without design changes * elapsed test and certification time * defects per unit (for example, number of fixes required to be safety compliant) * hours of actual test time vs.standard test time What metrics are you using and how well are they working? Richard Woods Sensormatic Electronics
RE: Safety Critical etc - the future
Hi Folks Having just logged on this morning, I am somewhat surprised at some of the comments against the concept of standard definitions for safety critical, compliance critical, etc. The very fact that this thread was started in one country and has spread across national boundaries with a wide range of opinions is evidence of the confusion that exists and the need for clarifications. After all we do already a huge range of definitions in the International Electrotechnical Vocabulary (IEV) - and an additional number in individual standards - for the very purpose of making life more straightforward for all us, and avoiding confusion, reinventing the wheel, etc. I was not, and am not, arguing that IEC committees and test authorites should define absolutely what is, and what is not, a safety critical, safety related, a compliance critical (etc) component. What I am saying, at least at this stage, is that the general meanings of these terms (and/or of any other terms that are chosen) shall be clarified in that forum so that - from one person/test house/authority/country to another - we can avoid confusion between component standards-compliance critical and overall equipment/system safety critical - a distinction on which most of us (at least those have realised the difference!) already seem to agree. That is not to say that there is no overlap between the terms as a single component can be one or the other - OR BOTH - dependent on what it is and what its function(s) and failure mode(s) is (are). In fact, as is quite obvious, that a component (e.g a transistor bias resistor in an SELV circuit) in a specific item of equipment may not be compliance critical for that equipment, but could be safety critical in the context of the role that equipment (or the system into which it is then integrated) such that if the component fails (etc) the overall equipment/system fails or fails to operate in a manner which ensures that safety is assured. For example: resistor in fuel feed valve in aircraft engine fails to open circuit- fuel valve does not open -engine stops but no fire, etc.- plane falls out of sky = UNSAFE condition!! After the general definitions have been agreed, then, maybe, we can go further by concensus between all the interested parties in the definitions of - particularly - compliance critical components which is what I think sparked this whole thread off! Regards John Allen Thales Defence Communications Division Bracknell, UK --- 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.
more glitches
The Elusive Glitch - Part 2 Hi All, This month, I describe in my Technical Tidbit article (www.dsmith.org) a way to accurately pinpoint the source of a waveform glitch. It takes last month's article one step further than just determining if a glitch is likely coming from an external source instead of the circuit being measured. The technique uses an extra channel(s) of a scope to determine if the glitch is real or a result of external EMI and is reminiscent of the amateur radio transmitter hunts I participated in as a teenager (except in the time domain this time). Knowing this information can save a lot of engineering time in the lab and has become more important as circuits and measurement instruments have increased in speed. Equipment can now be affected by EMI sources that have not been a problem until the last few years. Doug -- --- ___ _ Doug Smith \ / ) P.O. Box 1457 = Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-( ) | o |Email: d...@dsmith.org \ _ /]\ _ / Website: http://www.dsmith.org --- --- 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.
