Re: SV: Selection of Directives
I read in !emc-pstc that am...@westin-emission.no wrote (in LFENJLPMMJB mhpeibnilaepjcbaa.am...@westin-emission.no) about 'SV: Selection of Directives', on Sat, 5 Jan 2002: I wish I had seen this magical matrix, but unfortunately I have not. I assume that a matrix like this would be very complex and comprehensive. No, a matrix is perhaps the best way of handling the subject Example: An ITE would have to qualify for EMCD and maybe RTTE, RTTE only in respect of any relevant interface. maybe also LVD if the voltages are within the scope Yes. Quite normal. and if it is placed in an explosive area then the ATEX directive might also apply. Well, it would apply. A lot of maybe's and if's No, the matter seems quite clear. What uncertainty do you have in mind? ... I think we have to gain knowledge about a lot of the directives in order to know if a product falls within it. A matrix can not include that type of experience I think. Header and one line of a matrix: EquipmentLVDEMCD RTTE ATEX ITEYESYESModem interfaceOnly if intended for Bluetooth explosive atmosphere I'm looking forward to hear other inputs from the list members. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. --- 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: EMC-related safety issues
I read in !emc-pstc that cherryclo...@aol.com wrote (in 43.47bb025.29689...@aol.com) about 'EMC-related safety issues', on Sat, 5 Jan 2002: The one in a billion John refers to sounds very dramatic and difficult. More dramatic than you 'infant daughter' and '40 mph past a school'? I explained in VERY GREAT DETAIL the effect of cumulative probability in requiring very low probability events to be taken into account. In principle, as the probability goes down, the number of risk scenarios increases *combinatorially*. There is no Olber's Paradox in this area, the 'night sky is infinitely brighter than the Sun'! So it may be helpful to refer to IEC 61508 which is a recently-published 'basic safety publication' covering The functional safety of electrical / electronic / programmable safety-related systems IEC 61508 uses the concept of the Safety Integrity Level (or SIL) to help design safety-related systems which have quantified failure probabilities. The SILs for average probability of failure to perform design function on demand are: SIL level 1: up to 10^ -2 SIL level 2: 10^ -2 to 10^ -3 SIL level 3: 10^ -3 to 10^ -4 SIL level 4: 10^ -4 to 10^ -5 or even lower levels The SILs for average probability of dangerous failure per hour of operation are: SIL level 1: up to 10^ -6 SIL level 2: 10^ -6 to 10^ -7 SIL level 3: 10^ -7 to 10^ -8 SIL level 4: 10^ -8 to 10^ -9 or even lower levels The standard describes how to select the SIL level for a particular safety-related application, and we find that SIL4 is required where a failure of the safety system could result in the deaths or serious injuries of large numbers of people. Yes, my 10^-9 figure was in the context of your 'relatives sobbing all over the courtroom'. Most safety-related applications that most practising engineers will be involved in will be SIL1 or 2, maybe even SIL3, and hence require very much lower reliability than one in a billion. You are neglecting cumulative probability, in spite of quoting my whole text on it! SIL2, if it is applied to individual risk scenarios, is a recipe for disaster if you are putting many thousands of units, such as PCs or TVs, into the field. If is it applied, as it should be, to the cumulative probability of ALL risk scenarios, then *each one* needs to be constrained to that 10^-9 probability, preferably well below it. 100 scenarios at 10^-9 each gives a cumulative of 10^-7, after all. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. --- 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: EMC-related safety issues
I read in !emc-pstc that cherryclo...@aol.com wrote (in 132.6f59d2b.296 89...@aol.com) about 'EMC-related safety issues', on Sat, 5 Jan 2002: Dear Cortland People can't simply say: ordinary semiconductors won't demodulate RF levels produced by an unintentional radiator even the smallest amount of RF can be demodulated there are no hysteresis or threshold effects in a PN semiconductor junction or FET that is biased into its conduction region (at least not until you get below signal levels equivalent to less than a single electron). The question is not whether demodulation occurs, but whether the recovered modulation is at a level to cause a problem. 1 mV of r.f. can't produce even 1 mV of recovered modulation. What I am sure most engineers would really mean to say is: ordinary semiconductors exposed to RF levels from an information technology product which is fully compliant with all relevant EMC emissions standards and is at 10 metres distance will generally not demodulate a sufficient level of interference to make an appreciable difference to most electronic systems. I don't think most engineers would go along with a statement with such a high fog-factor. That is one of the points of contention; this subject seems to attract fog-factor like a superconducting magnet. Now we have a statement which has some scientific rigor and some engineering validity to it. Are you seriously putting that forward? It's so vague, IMO, as to be not useful; it does not help in any way to realise solutions. (Although I do worry that in Europe our harmonised EMC standards only test emissions up to 1GHz, so what does that say about the possible emitted fields strengths from a PC with a 1.2GHz clock frequency?) Extension up to 3 GHz (much higher in some cases) is being studied intensively. One major problem is that repeatable measurements above 1 GHz are very difficult to achieve. Let's see if we can put some meat into this discussion with a real-life example... Well, it's a very extreme case of real life! I doubt that you'll come across another one before you retire! I once tested a blood sample incubator for RF field immunity. When was this? Before or after 1976, when EMC of medical equipment first (AFAIK) surfaced as a matter to be studied intensively. [Big snip] How many people reading this would be now be quite happy to place even a fully-compliant PC (compliant at 10 metres distance, that is) right next to the unmodified incubator? If it helps, imagine that it is your young daughter whose blood sample is in the incubator to discover which drugs she needs to survive. Shall we have a vote on how close we would be prepared to place the PC? Might be interesting. This appeal to emotion is out of place. Let's not even think about the problems of proximity to cellphones and other intentional radiators. I didn't mention that the incubator was a small model used for mobile screening, for installation in a truck adapted for medical screening purposes which travels to various communities and parks there for a few days while it tests the local people for disease - hardly a very well controlled electromagnetic environment. What does the above imply for similar incubators in countries that do not have mandatory EMC immunity standards? Or for older incubators in the EU that have never had to meet the EMC directive? (Please don't reply with the old chestnut that we haven't heard of any problems so far, so everything must be OK - people who should have known better were using that phrase before September 11th. It is just not an acceptable argument where safety issues are involved, as any expert in safety law will tell you. Try: I've been driving past that school at 40mph for ten years and haven't hit a kid yet, so it must be safe mustn't it? as a test of the concept.) More emotion. This is another point of contention: as soon as any critique is offered to some pronouncement, these emotional arguments are trotted out. I had a similar experience with a militant carer of disabled people. Anything that suggested that her views were perhaps just a *little* extreme (like scrapping all London's black cabs overnight because they won't accommodate a wheelchair with the user in it) was greeted with 'Oh, so you are prejudiced against disabled people, are you?' IMO, your reasoning is utterly unreasonable. Designers are not omniscient, or had better assume they are not. So they must assume that they have not thought of every possible scenario down to that 10^-9 probability. How, then, can the designer be reasonably assured that his design is satisfactory, if he cannot rely on the absence of reports of problems? Is he to continue to refine it for years and years, before releasing
Re: EMC-related safety issues
I read in !emc-pstc that cherryclo...@aol.com wrote (in 92.1f676722.296 88...@aol.com) about 'EMC-related safety issues', on Sat, 5 Jan 2002: I am truly sorry if I irritated you by misunderstanding your words, but I took your posting to imply that electronic circuits which are not designed as RF receivers would not respond very well to radio frequencies. They DON'T respond very well, if compared with a receiver. My example was not intended to be a full answer to your example (there are other postings which are dealing with that) just to indicate that the frequency response of slow and commonplace ICs can be very high indeed. Well, that is not really correct. The r.f is demodulated at the first junction (usually) and beyond that point the device is only handling the modulation, at much lower frequencies. I am sensitive to this issue because I keep on running across electronics designers who say things like: I don't need to worry about the RF immunity of my audio amplifier/motor controller/temperature/pressure/flow/weight/velocity measurement and control system (please delete where applicable) because the opamps I use have a GBW of under 1MHz so they won't see the RF which is of course complete bollocks (a UK phrase that I hope translates well enough for all emc-pstc subscribers). There are always some! And no, I still don't agree with you that only radio receivers are sensitive enough to RF to have a problem with what you are still calling 'unintentional emissions' (even though this term means very little in an international forum unless you define the relevant standards or laws). I think this term is quite legitimate and well-understood. If the equipment requires to emit in order to perform its intended function, it is an 'intentional emitter'. If it does not need to do so, but emits anyway, it is an 'unintentional emitter'. It is difficult to see how there could be any confusion or ambiguity about this. I think the problem you are concerned with is application dependant and we cannot make such broad assumptions. As I said earlier, most interference problems are caused by radio transmitters or radio receivers, but not all. Well, electric fences -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. --- 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: EMC-related safety issues
The one in a billion John refers to sounds very dramatic and difficult. So it may be helpful to refer to IEC 61508 which is a recently-published 'basic safety publication' covering The functional safety of electrical / electronic / programmable safety-related systems IEC 61508 uses the concept of the Safety Integrity Level (or SIL) to help design safety-related systems which have quantified failure probabilities. The SILs for “average probability of failure to perform design function on demand” are: SIL level 1: up to 10^ -2 SIL level 2: 10^ -2 to 10^ -3 SIL level 3: 10^ -3 to 10^ -4 SIL level 4: 10^ -4 to 10^ -5 or even lower levels The SILs for ““average probability of dangerous failure per hour of operation” are: SIL level 1: up to 10^ -6 SIL level 2: 10^ -6 to 10^ -7 SIL level 3: 10^ -7 to 10^ -8 SIL level 4: 10^ -8 to 10^ -9 or even lower levels The standard describes how to select the SIL level for a particular safety-related application, and we find that SIL4 is required where a failure of the safety system could result in the deaths or serious injuries of large numbers of people. Most safety-related applications that most practising engineers will be involved in will be SIL1 or 2, maybe even SIL3, and hence require very much lower reliability than one in a billion. 'm sure that when we are driving our cars, or living near a nuclear plant, we would like to think that the designers of the braking system or control rod control systems (respectively) had looked at 'ALL risk scenarios down to the billion-to-one against level of probability' - to use John's words. Regards, Keith Armstrong In a message dated 04/01/02 19:31:57 GMT Standard Time, j...@jmwa.demon.co.uk writes: Subj:Re: EMC-related safety issues Date:04/01/02 19:31:57 GMT Standard Time From:j...@jmwa.demon.co.uk (John Woodgate) I read in !emc-pstc that cherryclo...@aol.com wrote (in 167.698dddc.296 70...@aol.com) about 'EMC-related safety issues', on Fri, 4 Jan 2002: As my paper at the IEEE's EMC Symposium in Montreal and my recent article in ITEM UPDATE 2001 show - at present EMC standards don't address safety issues, and most safety standards don't address EMC-related functional safety issues. As far as CENELEC is concerned, it was a conscious decision not to incorporate 'EMC and Safety' issues into EMC standards, but to treat it as a separate subject. Some people may find a clarification helpful. We have EMC matters, concerned with compatibility between items of equipment, ensuring that they continue to work (Criterion A in the Generic Standards) or fail gracefully (Criteria B and C). These criteria do not address safety issues, as indicated in paragraph 1 above. However, the Generic Standards do have a limited 'blanket' requirement, that equipment must not become unsafe *during testing*. We also have safety matters per se, which don't involve EMC. We ALSO have the separate subject, called 'EMC and Safety' or reasonable variants thereof. This addresses the matter of equipment becoming unsafe *in service* due to excessive emission levels in the environment, or lack of sufficient immunity to acceptable emission levels. So far, this seems perfectly reasonable. BUT it stops seeming reasonable when the question 'What could go wrong?' is asked and statistical data is used to attempt to answer it. To take a very simple example (maybe over-simplified), we might say that the probability of an unsafe occurrence should be less than 10^-9. That immediately means that the designer of the equipment has to look at ALL risk scenarios down to the billion-to-one against level of probability. To say that that is difficult is surely a great understatement. But some experts in the field seem to ignore that great difficulty, and simply (or maybe not so simply) state that if the designer fails to take into account ANY scenario that subsequently results in an unsafe condition, the designer has failed in his professional responsibility, and may be held criminally responsible for negligence. Well, let us be very circumspect designers and look at what immunity levels we might need to get down to that 10^-9 probability. For radiated emissions, the necessary test levels seem to be of the order of 100 V/m. Test levels for other disturbances seem to be equally distantly related to the levels normally experienced and to the test levels in pure EMC standards. We might conclude that assessment of EMC immunity per se is completely unnecessary, because testing for 'EMC and Safety' requires test levels of the order of 30 dB higher! One could go, with the sort of reasoning advocated by some experts, further into the realms of fantasy. Suppose, for a particular piece of equipment, the designer, with great diligence, identifies a million threat scenarios, each of which has a probability of 10^-9. The cumulative probability of ANY ONE of them occurring
Re: EMC-related safety issues
In a message dated 04/01/02 19:31:51 GMT Standard Time, j...@jmwa.demon.co.uk writes: The trick, I believe, is not to be in that position in the first place. Design your products using the latest safety knowledge and test them well to discover if they have any weaknesses you did not address. How do you decide what tests to do **for weaknesses you don't suspect**? Isn't that fundamentally impossible? I actually said for weaknesses you did not address not for weaknesses you did not suspect - quite a different matter. Mind you, if a designer is not very competent in safety matters there might be quite a number of things that he/she did not suspect, much less address, that he/she should have done. But I was thinking of tests such as bump and vibration, thermal extremes, etc, that reputable companies do to test the reliability of their products. Also safety tests such as simulating faults in components (such as shorting or opening power transistors and capacitors, disconnecting connections to resistors and ICs, etc.). These tests tend to reveal many safety issues that were overlooked in the heat of the design process, or through lack of knowledge of the design staff, and sometimes even reveal things that safety experts familiar with the product type would not have expected. Because such tests can be done and are available from many suppliers (if you don't do them yourself) I understand from UK safety enforcers (Trading Standards) that a manufacturer would have a hard time proving compliance with the LVD or PLD directives if using them would have revealed a safety problem that contributed to an actual safety incident. Regards, Keith Armstrong
Re: EMC-related safety issues
Dear Cortland People can't simply say: ordinary semiconductors won't demodulate RF levels produced by an unintentional radiator – even the smallest amount of RF can be demodulated – there are no hysteresis or threshold effects in a PN semiconductor junction or FET that is biased into its conduction region (at least not until you get below signal levels equivalent to less than a single electron). What I am sure most engineers would really mean to say is: ordinary semiconductors exposed to RF levels from an information technology product which is fully compliant with all relevant EMC emissions standards and is at 10 metres distance will generally not demodulate a sufficient level of interference to make an appreciable difference to most electronic systems. Now we have a statement which has some scientific rigor and some engineering validity to it. (Although I do worry that in Europe our harmonised EMC standards only test emissions up to 1GHz, so what does that say about the possible emitted fields strengths from a PC with a 1.2GHz clock frequency?) Let's see if we can put some meat into this discussion with a real-life example... I once tested a blood sample incubator for RF field immunity. The incubator was used during screening programs (for cancer and other diseases) and kept about 100 test tubes at 37.1C (normal blood temperature), while the reagents in the test tubes changed colour. After 24 hours of incubation medical staff would inspect the test tubes and write letters to people telling them they were sick, or that they were clear of the disease. I don't know what temperature tolerance the reagents had to give an accurate medical diagnosis, so assume ±0.1C. On the front panel of the incubator was a display of its temperature, which was of course 37.1C. We found that field strengths as low as 1V/m would cause the incubation temperature to range over full scale, from heaters fully off (in which case the temperature would decline to ambient) to maximum (in which case the water used to incubate the test tubes would boil). We could use the RF test frequency to control the temperature between plus and minus full scale over the frequency range 80 to 1000MHz at 1V/m (and did not test beyond 1GHz). Most worryingly, the front panel display would only show temporary variations from its 37.1C when the RF field was turned off or on, and would continue to show 37.1C even when the water in the incubator was stone cold or actually boiling. Most demodulation effects in bipolar and FET devices approximate to a square law - for example a 1dB fall in the field strength (keeping everything else constant) would typically result in a 2dB fall in the demodulated 'interference' error signal, as John Woodgate has recently pointed out. If we assume that the 1V/m field strength was causing a 60C temperature error, how low would we need to make the RF field to get down to the 0.1C accuracy of the front panel display? Assuming square-law characteristics for the device doing the demodulation I calculate a field strength of around 40mV/m or 92dBmicrovolts/metre. You will notice that I have been generous to the incubator and assumed that the 1V/m field just about caused its temperature error to increase by 60C to boil the water, whereas it could have been overdriving the internal circuits by a considerable margin and still suffered a 60C error at 0.1V/m. We didn't test this possibility as our focus was (as in most of these cases) on quickly modifying the product so it passed the immunity test - which we did. 92dBmicrovolts/metre is not a very high RF field level for a PC without any EMC precautions at a distance of 10 metres. How many people reading this would be now be quite happy to place even a fully-compliant PC (compliant at 10 metres distance, that is) right next to the unmodified incubator? If it helps, imagine that it is your young daughter whose blood sample is in the incubator to discover which drugs she needs to survive. Shall we have a vote on how close we would be prepared to place the PC? Might be interesting. Let's not even think about the problems of proximity to cellphones and other intentional radiators. I didn't mention that the incubator was a small model used for mobile screening, for installation in a truck adapted for medical screening purposes which travels to various communities and parks there for a few days while it tests the local people for disease - hardly a very well controlled electromagnetic environment. What does the above imply for similar incubators in countries that do not have mandatory EMC immunity standards? Or for older incubators in the EU that have never had to meet the EMC directive? (Please don't reply with the old chestnut that we haven't heard of any problems so far, so everything must be OK - people who should have known better were using that phrase before September 11th. It is just not an acceptable
Re: EMC-related safety issues
Dear Ken That is exactly what I am saying: under the EU's Product Liability Directive a company can be held liable for unlimited damages with no proof of negligence on the manufacturer's part. It is of course a valid management decision to ignore a market that is almost as large as USA/Canada because of financial risk issues – but you'll notice that a lot of manufacturers are still making lots of money selling goods in the EU. Regards, Keith Armstrong In a message dated 05/01/02 01:31:03 GMT Standard Time, ken.ja...@emccompliance.com writes: Subj:Re: EMC-related safety issues Date:05/01/02 01:31:03 GMT Standard Time From:ken.ja...@emccompliance.com (Ken Javor) To:cherryclo...@aol.com, emc-p...@majordomo.ieee.org Interesting to note that this country (USA) got started in part because of a tax on tea. I think you are saying here that a company can be held liable for unlimited damages with no proof of negligence on the manufacturer's part. If I were a manufacturer I would simply not market to the EU.
Re: EMC-related safety issues
Dear Ken
That is precisely the point I was trying to make: all companies (and people)
always weigh up all the costs and risks that they know about and act
accordingly.
The problem arises when certain risks are unknown or ignored, for whatever
reasons.
I see it as part of every engineer's job to inform the people who make the
cost/risk decisions about all the costs and risks associated with a certain
course of action.
What I find in practice is that most engineers are aware of the costs but as
it is so hard to quantify the risks they often don't bother. Also, many
engineers are uncomfortable with quoting numbers that they can't accurately
calculate to five decimal places.
Hands up all those whose formal (or in-company) engineering education
included risk analysis and estimation and how to present the data to
management
So in many cases management don't have the full information on which to base
their cost/risk decisions.
Regards, Keith Armstrong
In a message dated 05/01/02 01:27:34 GMT Standard Time,
ken.ja...@emccompliance.com writes:
Subj:Re: EMC-related safety issues
Date:05/01/02 01:27:34 GMT Standard Time
From:ken.ja...@emccompliance.com (Ken Javor)
To:cherryclo...@aol.com, emc-p...@majordomo.ieee.org
My take on it is that rather than appease ridiculous demands, a company
ought to look at the profit vs. risk vs. cost to consumer and decide, heck,
it ain't worth it. Case in point on the news today I heard that DPT shots
are in short supply, because two companies quit making it. They quit
making it because there were a very small number of bad reactions to it and
there were lawsuits or gov't action. Well, my kids are beyond that stage
but I sure feel sorry for the people out there whose infants are at risk
for whooping cough, diphtheria and pertussis. The only thing worse than
watching your child become seriously ill is knowing it was easily
preventable.
S on 1/4/02 7:37 AM, cherryclo...@aol.com at cherryclo...@aol.com wrote:
Hey, Ken, let's try to be realistic here!
Sure - we should try to get laws we don't like changed, but that isn't
going to happen overnight and in the meantime we have to operate within
the law as it stands.
Or are you suggesting immediate insurrection by product manufacturers?
(Outlaw manufacturers roaming the wild wild west - an interesting
concept!)
The IEE's guide on EMC and Functional Safety is concerned with such legal
aspects, but is also concerned with saving lives in a world where
electronic control of safety-related functions is proliferating madly.
As my paper at the IEEE's EMC Symposium in Montreal and my recent article
in ITEM UPDATE 2001 show - at present EMC standards don't address safety
issues, and most safety standards don't address EMC-related functional
safety issues.
Regards, Keith Armstrong
In a message dated 03/01/02 17:24:42 GMT Standard Time,
ken.ja...@emccompliance.com writes:
Subj:Re: EMC-related safety issues
Date:03/01/02 17:24:42 GMT Standard Time
From:ken.ja...@emccompliance.com (Ken Javor)
Sender:owner-emc-p...@majordomo.ieee.org
Reply-to: ken.ja...@emccompliance.com (Ken Javor)
To:c...@dolby.co.uk (James, Chris), acar...@uk.xyratex.com
('acar...@uk.xyratex.com'), emc-p...@majordomo.ieee.org
There is an inherent contradiction in this anti-profit, anti-technology
point-of-view that I cannot and will not defend. All I am saying is that
people who feel this is wrong should stand up and say so, not write
guides for how to go along with it.
Re: EMC-related safety issues
Dear Ken I am truly sorry if I irritated you by misunderstanding your words, but I took your posting to imply that electronic circuits which are not designed as RF receivers would not respond very well to radio frequencies. My example was not intended to be a full answer to your example (there are other postings which are dealing with that) just to indicate that the frequency response of slow and commonplace ICs can be very high indeed. I am sensitive to this issue because I keep on running across electronics designers who say things like: I don't need to worry about the RF immunity of my audio amplifier/motor controller/temperature/pressure/flow/weight/velocity measurement and control system (please delete where applicable) because the opamps I use have a GBW of under 1MHz so they won't see the RF – which is of course complete bollocks (a UK phrase that I hope translates well enough for all emc-pstc subscribers). And no, I still don't agree with you that only radio receivers are sensitive enough to RF to have a problem with what you are still calling 'unintentional emissions' (even though this term means very little in an international forum unless you define the relevant standards or laws). I think the problem you are concerned with is application dependant and we cannot make such broad assumptions. As I said earlier, most interference problems are caused by radio transmitters or radio receivers, but not all. Regards, Keith Armstrong In a message dated 05/01/02 01:20:27 GMT Standard Time, ken.ja...@emccompliance.com writes: Subj:Re: EMC-related safety issues Date:05/01/02 01:20:27 GMT Standard Time From:ken.ja...@emccompliance.com (Ken Javor) To:cherryclo...@aol.com, emc-p...@majordomo.ieee.org One sure way to REALLY irritate me is to twist my words and try to make me look stupid (I do a fine job by myself on occasion and don't appreciate any outside help). I did not say that pn junctions don't detect and rectify rf, I said that the field intensities associated with unintentional emissions from ITE are too low to cause susceptibility in circuits other than radios. Your example here is 10 V/m, and you are talking about an op-amp (gain unspecified) and that it was susceptible at that level should be no surprise to anyone. on 1/4/02 7:34 AM, cherryclo...@aol.com at cherryclo...@aol.com wrote: Does anyone else think that ordinary semiconductors doesn't respond to RF? I have tested a product which was little more than an LM324 quad op-amp for RF immunity using IEC 61000-4-3. This op-amp has a slew rate of 1V/micro-second on a good day with the wind in its favour. It was housed in an unshielded plastic enclosure. Demodulated noise that exceeded the (not very tough) product specification were seen all the way up to 500MHz at a number of spot frequencies that appeared to be due to the natural resonances of the input and output cables. Above 500MHz this resonant behaviour vanished to be replaced by a steadily rising level of demodulated 1kHz tone as the frequency increased. I stopped testing at 1GHz, where the output error from the product was about 10% and still rising with increased frequency. OK, the field strength for the test was 10V/m (unmodulated) but the real surprise was how well this very cheap and very slow opamp demodulated the RF, and that it demodulated better at 1GHz than at 500MHz. I have done many many immunity tests using IEC 61000-4-3 on audio equipment and found much the same effects with every product I've ever tested. With most larger products there is usually a roll-off in the demodulation above 500MHz - not because the semiconductors in the ICs can't respond (they can) but apparently because larger products have higher losses above 500MHz or so between the cable ports and the semiconductors, plus a denser structure that might provide more self-screening. The transistors and diodes in all modern ICs (analog or digital) are so tiny that they make excellent detectors at UHF and beyond. As they get smaller (and they are) their frequency response increases (and their vulnerability to upset and damage decreases). Regards, Keith Armstrong
Re: SV: Selection of Directives
Dear All A page on our website www.cherryclough.com has a useful list of EU directives relating to electronic products (and not just the CE marking ones) and the URLs where they and lists of their relevant standards can be downloaded from. Not every possible directive is covered, but I think most of the relevant ones are. As for a directives matrix - what a wonderful idea, but I've never seen one and don't expect to - it would be just too complicated. Regards, Keith Armstrong In a message dated 05/01/02 15:15:53 GMT Standard Time, am...@westin-emission.no writes: Subj:SV: Selection of Directives Date:05/01/02 15:15:53 GMT Standard Time From:am...@westin-emission.no Sender:owner-emc-p...@majordomo.ieee.org Reply-to: A HREF=mailto:am...@westin-emission.no;am...@westin-emission.no/A To:emc-p...@majordomo.ieee.org Hi Sam, I wish I had seen this magical matrix, but unfortunately I have not. I assume that a matrix like this would be very complex and comprehensive. Example: An ITE would have to qualify for EMCD and maybe RTTE, maybe also LVD if the voltages are within the scope and if it is placed in an explosive area then the ATEX directive might also apply. A lot of maybe's and if's ... I think we have to gain knowledge about a lot of the directives in order to know if a product falls within it. A matrix can not include that type of experience I think. I'm looking forward to hear other inputs from the list members. Amund -Opprinnelig melding- Fra: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]På vegne av Sam Wismer Sendt: 4. januar 2002 16:22 Til: EMC Forum Emne: Selection of Directives Hi all, Me again….. My primary focus over the last few years has been limited to ITE and 2.4GHz SS radio products. My contact lists and web page book marks are filled with the necessary links to information regarding these types of products and I am very comfortable with obtaining compliance with the required Directives that apply.I am now exposed to many types of products destined for the EU and want to make sure to apply the proper directives and standards. Where is the magical matrix that one can pick his directive and test suite from for a given type of product? Kind Regards, Sam Wismer Engineering Manager ACS, Inc. Phone: (770) 831-8048 Fax: (770) 831-8598 Web: www.acstestlab.com
SV: Selection of Directives
Hi Sam, I wish I had seen this magical matrix, but unfortunately I have not. I assume that a matrix like this would be very complex and comprehensive. Example: An ITE would have to qualify for EMCD and maybe RTTE, maybe also LVD if the voltages are within the scope and if it is placed in an explosive area then the ATEX directive might also apply. A lot of maybe's and if's ... I think we have to gain knowledge about a lot of the directives in order to know if a product falls within it. A matrix can not include that type of experience I think. I'm looking forward to hear other inputs from the list members. Amund -Opprinnelig melding- Fra: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]Pa vegne av Sam Wismer Sendt: 4. januar 2002 16:22 Til: EMC Forum Emne: Selection of Directives Hi all, Me again... My primary focus over the last few years has been limited to ITE and 2.4GHz SS radio products. My contact lists and web page book marks are filled with the necessary links to information regarding these types of products and I am very comfortable with obtaining compliance with the required Directives that apply.I am now exposed to many types of products destined for the EU and want to make sure to apply the proper directives and standards. Where is the magical matrix that one can pick his directive and test suite from for a given type of product? Kind Regards, Sam Wismer Engineering Manager ACS, Inc. Phone: (770) 831-8048 Fax: (770) 831-8598 Web: www.acstestlab.com
Re: EMC-related safety issues
I read in !emc-pstc that John Shinn john.sh...@sanmina-sci.com wrote (in 002401c19584$35f73660$0b3d1...@hadco.comsanmina.com) about 'EMC- related safety issues', on Fri, 4 Jan 2002: So where do I drill the hole in my fuel injection system? You don't. You put a pint of water in the tank and a spoonful of liquid detergent to make it mix with the fuel. Don't forget to replace the whole engine after you've passed the emission test. (;-) -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. --- 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: EMC-related safety issues
I read in !emc-pstc that Ken Javor ken.ja...@emccompliance.com wrote (in b85bb29d.c04%ken.ja...@emccompliance.com) about 'EMC-related safety issues', on Fri, 4 Jan 2002: My take on it is that rather than appease ridiculous demands, a company ought to look at the profit vs. risk vs. cost to consumer and decide, heck, it ain't worth it. Case in point on the news today I heard that DPT shots are in short supply, because two companies quit making it. They quit making it because there were a very small number of bad reactions to it and there were lawsuits or gov't action. Well, my kids are beyond that stage but I sure feel sorry for the people out there whose infants are at risk for whooping cough, diphtheria and pertussis. Ahem, whooping cough IS pertussis. 'DPT' = Diphtheria, pertussis and tetanus. The only thing worse than watching your child become seriously ill is knowing it was easily preventable. This is wildly OT, but there is a big issue in Britain in this area, because what we call the 'triple vaccine' or 'MMR' (measles, mumps and rubella) is alleged to be implicated in autism and serious bowel disorders. The connection is, AIUI, considered by a *small* number of qualified medical people, to be proved, or very probable. This is another case of (alleged) dire results of a very low probability, but much higher that my suggested 'generic' 10^-9 level. The government has, if anything, made matters worse, by denying parents the right to choose, on the National Health (free) Service, three separate vaccinations instead of the triple, so it's the triple or none and it seems about 20% of parents are choosing 'none', in addition to the 10% or so who reject or do not bother about vaccination per se. With only 70% of infants vaccinated, there is a real risk of an epidemic. Matters were made even worse by the indignant reaction of the Prime Minister, who refused to answer in Parliament when asked if his infant son has had the triple vaccine! The implication is that the PM has paid for three separate vaccinations instead. I believe also that the DPT vaccine is not licensed in Europe because of the (alleged) incidence of serious side-effects. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. --- 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: Magnetic measurement per CISPR 15
It is my understanding that the conversion factor converts the voltage reading on a 50 ohm receiver to the amperage reading directly. In other words, 1dbuV *is* 1dBuA and already takes into account the 50 ohm input impedance. Sadly, all this was written before advancements in electronics occured. For example, I designed and built a small portable magnetic preamp I use for measuring magnetic fields. It has a 4 inch diameter air core coil, produces 1 V per microTesla over the frequency range of 5 Hz to 1 MHz with a noise floor of around 5 nT (the noise coefficient is dropping as a function of frequency and integrates over the bandwidth) so most of the noise energy is around the 5 to 100 Hz range. It was originally designed to address the Swedish MPRII rules. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: KC CHAN [PDD] kcc...@hkpc.org To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Friday, January 04, 2002 8:57 PM Subject: Magnetic measurement per CISPR 15 Hi all I got a question about the magnetic measurement per CISPR 15, it says that the sensitivity of the current probe is 1V/A. My interpretation is that X dBuV measurement you got from the EMI receiver, corresponding to XdBuA, which is then compared to the limit, say 88dBuA at 50 kHz for 2-m 3-loop system. The manual I have says the same thing. Is it correct? My question is 1) Do we need to covert the voltage to current taking consideration of the 50 Ohm impedance of the receiver? If that is the case, we need to minus 34 dB from my voltage measurement to get the current measurement . 2) In what ways the whole system has considered the impedance variation of the current probe impedance. I have checked the impedance of the current probe, the impedance is ranging from 40+ Ohm at 10kHz to 150+ Ohm at around 150K and decreases to around 75 Ohm at 1 MHZ. Thank you KC Chan --- 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.
[SI-LIST] job postings
Hi All, I have a page on my website where I post both positions available and persons looking for positions. I do this as a service (no charge for the posting). Three new positions have been added in the last few days, one this evening from Maryland. The direct URL of the page is: http://emcesd.com/jobs/jobpost.htm This page contains only job posts, no technical stuff or ads. If you want to post a position feel free to send me an mail and will put it up for you. If others on this list have similar job posting pages, perhaps they can also share them also. 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 --- -- To unsubscribe from si-list: si-list-requ...@freelists.org with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-requ...@freelists.org with 'help' in the Subject field List archives are viewable at: http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu
Magnetic measurement per CISPR 15
Hi all I got a question about the magnetic measurement per CISPR 15, it says that the sensitivity of the current probe is 1V/A. My interpretation is that X dBuV measurement you got from the EMI receiver, corresponding to XdBuA, which is then compared to the limit, say 88dBuA at 50 kHz for 2-m 3-loop system. The manual I have says the same thing. Is it correct? My question is 1) Do we need to covert the voltage to current taking consideration of the 50 Ohm impedance of the receiver? If that is the case, we need to minus 34 dB from my voltage measurement to get the current measurement . 2) In what ways the whole system has considered the impedance variation of the current probe impedance. I have checked the impedance of the current probe, the impedance is ranging from 40+ Ohm at 10kHz to 150+ Ohm at around 150K and decreases to around 75 Ohm at 1 MHZ. Thank you KC Chan --- 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: EMC-related safety issues
Hi Ken,
The reason that those companies stopped was because it was found
that there was mercury in the formulation of the vaccine. The mercury
had no other use other than stabilization. The mercury is known to
cause brain damage. Prior to around 1980, DPT was not given to infants.
The rise in autism has correlated with the increased use of the infant
vaccines.Those companies were also found to have poor process control
that allowed too much of a live virus in their vaccines causing a
so-called 'hot batch'. The company that is left doesn't have mercury in
their formulation and has superior process control. I would much rather
see my child suffer through a virus than be permanently brain
damaged(usually undetectably)
BTW, whooping cough and pertusis are the same thing. the D stands
for Diptheria.
Jim Freeman
Ken Javor wrote:
My take on it is that rather than appease ridiculous demands, a
company ought to look at the profit vs. risk vs. cost to consumer and
decide, heck, it ain't worth it. Case in point on the news today I
heard that DPT shots are in short supply, because two companies quit
making it. They quit making it because there were a very small number
of bad reactions to it and there were lawsuits or gov't action. Well,
my kids are beyond that stage but I sure feel sorry for the people out
there whose infants are at risk for whooping cough, diphtheria and
pertussis. The only thing worse than watching your child become
seriously ill is knowing it was easily preventable.
S on 1/4/02 7:37 AM, cherryclo...@aol.com at cherryclo...@aol.com
wrote:
Hey, Ken, let's try to be realistic here!
Sure - we should try to get laws we don't like changed, but
that isn't going to happen overnight and in the meantime we
have to operate within the law as it stands.
Or are you suggesting immediate insurrection by product
manufacturers?
(Outlaw manufacturers roaming the wild wild west - an
interesting concept!)
The IEE's guide on EMC and Functional Safety is concerned
with such legal aspects, but is also concerned with saving
lives in a world where electronic control of safety-related
functions is proliferating madly.
As my paper at the IEEE's EMC Symposium in Montreal and my
recent article in ITEM UPDATE 2001 show - at present EMC
standards don't address safety issues, and most safety
standards don't address EMC-related functional safety
issues.
Regards, Keith Armstrong
In a message dated 03/01/02 17:24:42 GMT Standard Time,
ken.ja...@emccompliance.com writes:
Subj:Re: EMC-related safety issues
Date:03/01/02 17:24:42 GMT Standard Time
From:ken.ja...@emccompliance.com (Ken Javor)
Sender:owner-emc-p...@majordomo.ieee.org
Reply-to: ken.ja...@emccompliance.com (Ken Javor)
To:c...@dolby.co.uk (James, Chris),
acar...@uk.xyratex.com ('acar...@uk.xyratex.com'),
emc-p...@majordomo.ieee.org
There is an inherent contradiction in this
anti-profit, anti-technology point-of-view that I
cannot and will not defend. All I am saying is
that people who feel this is wrong should stand up
and say so, not write guides for how to go along
with it.
Re: Primary Power Range on a Product Label ...
Doug, For -48 Vdc equipment, the 3rd edition of CSA/UL 60950 gives a should in Annex NAB.2 unless otherwise specified by the manufacturer... It is worth a look. taniagr...@msn.com - Original Message - From: Doug McKean dmck...@auspex.com To: EMC-PSTC Discussion Group emc-p...@majordomo.ieee.org Sent: Friday, January 04, 2002 4:17 PM Subject: Primary Power Range on a Product Label ... I've never had an NRTL actually tell me what the specific domestic voltage *should* be. Either one is okay. I'm fairly certain you could get by with 100-115 as well. You probably know already, but keep in mind the primary voltage range placed on the label of a product directly sets the upper (+6%) and lower (-10%) limits of HI/LO line testing at an NRTL. 100-120V yields 90 and 132 100-127V yields 90 and 135 A difference of 3 volts on the upper side might not matter. Then again, it might. - 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. --- 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: EMC-related safety issues
Interesting to note that this country (USA) got started in part because of a tax on tea. I think you are saying here that a company can be held liable for unlimited damages with no proof of negligence on the manufacturer's part. If I were a manufacturer I would simply not market to the EU. on 1/4/02 7:39 AM, cherryclo...@aol.com at cherryclo...@aol.com wrote: As I understand the way the civil law section of the EU's Product Liability Directive operates (I am not a lawyer) it does in fact place the burden of proof on the manufacturer, who is effectively considered 'guilty until proved innocent'. I also understand that any number of manufacturers can be sued in the civil courts under one safety incident, and the liabilities of each awarded 'on the balance of probabilities' that their product caused the damage, injury or death being complained about. Also...nobody has to prove negligence on the part of the manufacturer, this is sometimes called 'no-fault liability' - you can be held to be liable under the law even though nobody has proved that your product was actually the cause of the safety incident. Another interesting fact about EU Product Liability is that in the civil courts in most EU member states there is no financial upper limit to the damages that can be awarded against a manufacturer. We may not like it, but that's how the world appears to be at the moment. Regards, Keith Armstrong In a message dated 03/01/02 19:52:20 GMT Standard Time, j...@jmwa.demon.co.uk writes: Subj:Re: EMC-related safety issues List-Post: emc-pstc@listserv.ieee.org Date:03/01/02 19:52:20 GMT Standard Time From:j...@jmwa.demon.co.uk (John Woodgate) Sender:owner-emc-p...@majordomo.ieee.org Reply-to: j...@jmwa.demon.co.uk (John Woodgate) To:emc-p...@majordomo.ieee.org I read in !emc-pstc that Gary McInturff Gary.McInturff@worldwidepackets .com wrote (in 917063bab0ddb043af5faa73c7a835d40ac...@windlord.wwp.com ) about 'EMC-related safety issues', on Thu, 3 Jan 2002: While I take your point - I'll challenge with the equally valid argument that says show me the data that they do cause SIDS! Out of order! That's the whole point! Manufacturers are being required to prepare to prove a negative, which is inherently impossible in most cases. No-one is required to prove a positive, which is easy if it is true.
Re: EMC-related safety issues
My take on it is that rather than appease ridiculous demands, a company
ought to look at the profit vs. risk vs. cost to consumer and decide, heck,
it ain't worth it. Case in point on the news today I heard that DPT shots
are in short supply, because two companies quit making it. They quit making
it because there were a very small number of bad reactions to it and there
were lawsuits or gov't action. Well, my kids are beyond that stage but I
sure feel sorry for the people out there whose infants are at risk for
whooping cough, diphtheria and pertussis. The only thing worse than
watching your child become seriously ill is knowing it was easily
preventable.
S on 1/4/02 7:37 AM, cherryclo...@aol.com at cherryclo...@aol.com wrote:
Hey, Ken, let's try to be realistic here!
Sure - we should try to get laws we don't like changed, but that isn't going
to happen overnight and in the meantime we have to operate within the law as
it stands.
Or are you suggesting immediate insurrection by product manufacturers?
(Outlaw manufacturers roaming the wild wild west - an interesting concept!)
The IEE's guide on EMC and Functional Safety is concerned with such legal
aspects, but is also concerned with saving lives in a world where electronic
control of safety-related functions is proliferating madly.
As my paper at the IEEE's EMC Symposium in Montreal and my recent article in
ITEM UPDATE 2001 show - at present EMC standards don't address safety
issues, and most safety standards don't address EMC-related functional
safety issues.
Regards, Keith Armstrong
In a message dated 03/01/02 17:24:42 GMT Standard Time,
ken.ja...@emccompliance.com writes:
Subj:Re: EMC-related safety issues
List-Post: emc-pstc@listserv.ieee.org
Date:03/01/02 17:24:42 GMT Standard Time
From:ken.ja...@emccompliance.com (Ken Javor)
Sender:owner-emc-p...@majordomo.ieee.org
Reply-to: ken.ja...@emccompliance.com (Ken Javor)
To:c...@dolby.co.uk (James, Chris), acar...@uk.xyratex.com
('acar...@uk.xyratex.com'), emc-p...@majordomo.ieee.org
There is an inherent contradiction in this anti-profit, anti-technology
point-of-view that I cannot and will not defend. All I am saying is that
people who feel this is wrong should stand up and say so, not write guides
for how to go along with it.
Re: EMC-related safety issues
One sure way to REALLY irritate me is to twist my words and try to make me
look stupid (I do a fine job by myself on occasion and don't appreciate any
outside help). I did not say that pn junctions don't detect and rectify rf,
I said that the field intensities associated with unintentional emissions
from ITE are too low to cause susceptibility in circuits other than radios.
Your example here is 10 V/m, and you are talking about an op-amp (gain
unspecified) and that it was susceptible at that level should be no surprise
to anyone.
on 1/4/02 7:34 AM, cherryclo...@aol.com at cherryclo...@aol.com wrote:
Does anyone else think that ordinary semiconductors doesn't respond to RF?
I have tested a product which was little more than an LM324 quad op-amp for
RF immunity using IEC 61000-4-3. This op-amp has a slew rate of
1V/micro-second on a good day with the wind in its favour. It was housed in
an unshielded plastic enclosure.
Demodulated noise that exceeded the (not very tough) product specification
were seen all the way up to 500MHz at a number of spot frequencies that
appeared to be due to the natural resonances of the input and output cables.
Above 500MHz this resonant behaviour vanished to be replaced by a steadily
rising level of demodulated 1kHz tone as the frequency increased. I stopped
testing at 1GHz, where the output error from the product was about 10% and
still rising with increased frequency.
OK, the field strength for the test was 10V/m (unmodulated) but the real
surprise was how well this very cheap and very slow opamp demodulated the
RF, and that it demodulated better at 1GHz than at 500MHz.
I have done many many immunity tests using IEC 61000-4-3 on audio equipment
and found much the same effects with every product I've ever tested.
With most larger products there is usually a roll-off in the demodulation
above 500MHz - not because the semiconductors in the ICs can't respond (they
can) but apparently because larger products have higher losses above 500MHz
or so between the cable ports and the semiconductors, plus a denser
structure that might provide more self-screening.
The transistors and diodes in all modern ICs (analog or digital) are so tiny
that they make excellent detectors at UHF and beyond. As they get smaller
(and they are) their frequency response increases (and their vulnerability
to upset and damage decreases).
Regards, Keith Armstrong
In a message dated 03/01/02 23:27:19 GMT Standard Time,
ken.ja...@emccompliance.com writes:
Subj:Re: EMC-related safety issues
List-Post: emc-pstc@listserv.ieee.org
Date:03/01/02 23:27:19 GMT Standard Time
From:ken.ja...@emccompliance.com (Ken Javor)
Sender:owner-emc-p...@majordomo.ieee.org
Reply-to: ken.ja...@emccompliance.com (Ken Javor)
To:m...@california.com (Robert Macy), ghery.pet...@intel.com (Pettit,
Ghery), james.col...@usa.alcatel.com ('James Collum'),
emc-p...@majordomo.ieee.org
Emissions from a laptop are naturally (without suppression) on the order of
10 uV/m to 100s of uV/m. 1000 uV/m would represent at least a 20 dB outage
at frequencies that could possibly interfere with sensor electronics. The
coupling is lossy: 1 mV/m will generate far less than 1 mV signal in the
electronics, and this at rf. Does anyone really see this as a remotely
possible mechanism? I don't.
--
From: Robert Macy m...@california.com
To: Pettit, Ghery ghery.pet...@intel.com, 'James Collum'
james.col...@usa.alcatel.com, emc-p...@majordomo.ieee.org
Subject: Re: EMC-related safety issues
Date: Thu, Jan 3, 2002, 3:25 PM
Perhaps, it merely interfered with the sensor electronics, not the true
magnetic field that was being sensed.
- Robert -
Robert A. Macy, PEm...@california.com
408 286 3985 fx 408 297 9121
AJM International Electronics Consultants
619 North First St, San Jose, CA 95112
-Original Message-
From: Pettit, Ghery ghery.pet...@intel.com
To: 'James Collum' james.col...@usa.alcatel.com;
emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org
Date: Thursday, January 03, 2002 11:46 AM
Subject: RE: EMC-related safety issues
I still have a hard time believing it was a compass that was affected by
a laptop computer. ADF indication, could be. VOR, maybe. Magnetic
compass? I wouldn't want a magnetic source that strong in my lap! My belt
buckle would be stuck to it. There is quite a distance between a magnetic
compass in the cockpit of an airliner and anything a passenger is carrying.
Not so in a Cessna 172, but in a DC-10?
Ghery Pettit
-Original Message-
From: James Collum [mailto:james.col...@usa.alcatel.com]
Sent: Thursday, January 03, 2002 10:47 AM
To: emc-p...@majordomo.ieee.org
Subject: Re: EMC-related safety issues
*
A routine flight over Dallas-Fort Worth was disrupted when one of
the compasses suddenly shifted
Re: EMC-related safety issues
We need to separate specific regulation from general. The FCC does not care if a radio front end is wide open, though it now requires scanning receivers to have 38 dB image rejection. This does not mean they have narrow front ends, however. A SW receiver with a 75 MHz If may well have nothing but a low-pass filter in front of it. Cortland (What I write here is mine alone. My employer does not Concur, agree or else endorse These words, their tone, or thought.) John Shinn wrote: Actually, if you consider that there are two issues here. First, the TV and Radio manufacturers are required to no longer have a wide-open front end ... --- 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: EMC-related safety issues
So where do I drill the hole in my fuel injection system? John -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Doug McKean Sent: Friday, January 04, 2002 2:37 PM To: EMC-PSTC Discussion Group Subject: Re: EMC-related safety issues RE: EMC-related safety issuesKyle Ehler wrote: Another point of trivia is that a fresh oil change and new air filter prior to having your vehicle smog tested will improve the emissions results. At one time there was available OTC a fuel additive that one could deploy to further skew the results in your favor. I knew a guy who drilled a small hole in the side of his carborator, attatched a hose setup that you would use for an acquirium the other end of which was put into a water bottle. While the car was in idle, he'd adjust a valve on the hose to a slow drip of water into the carborator. This setup was on an old truck of his and he always got terrifically low emissions readings. - 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. --- 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: EMC-related safety issues
As I recall, a tank of gasohol and a long trip down the freeway beforehand was another method. Of course it didn't work as well if you then got in a long waiting line for the test. -George S. -Original Message- From: Doug McKean [mailto:dmck...@auspex.com] Sent: Friday, January 04, 2002 2:37 PM To: EMC-PSTC Discussion Group Subject:Re: EMC-related safety issues RE: EMC-related safety issuesKyle Ehler wrote: Another point of trivia is that a fresh oil change and new air filter prior to having your vehicle smog tested will improve the emissions results. At one time there was available OTC a fuel additive that one could deploy to further skew the results in your favor. I knew a guy who drilled a small hole in the side of his carborator, attatched a hose setup that you would use for an acquirium the other end of which was put into a water bottle. While the car was in idle, he'd adjust a valve on the hose to a slow drip of water into the carborator. This setup was on an old truck of his and he always got terrifically low emissions readings. - 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. --- 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.
Primary Power Range on a Product Label ...
I've never had an NRTL actually tell me what the specific domestic voltage *should* be. Either one is okay. I'm fairly certain you could get by with 100-115 as well. You probably know already, but keep in mind the primary voltage range placed on the label of a product directly sets the upper (+6%) and lower (-10%) limits of HI/LO line testing at an NRTL. 100-120V yields 90 and 132 100-127V yields 90 and 135 A difference of 3 volts on the upper side might not matter. Then again, it might. - 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: Selection of Directives
Try starting with the following URL and drill downward for each directive where you will find guidance documents and the standards listed. http://europa.eu.int/comm/enterprise/newapproach/standardization/harmstds/re flist.html http://europa.eu.int/comm/enterprise/newapproach/standardization/harmstds/r eflist.html Richard Woods Sensormatic Electronics Tyco International -Original Message- From: Sam Wismer [mailto:swis...@bellsouth.net] Sent: Friday, January 04, 2002 10:22 AM To: EMC Forum Subject: Selection of Directives Hi all, Me again. My primary focus over the last few years has been limited to ITE and 2.4GHz SS radio products. My contact lists and web page book marks are filled with the necessary links to information regarding these types of products and I am very comfortable with obtaining compliance with the required Directives that apply.I am now exposed to many types of products destined for the EU and want to make sure to apply the proper directives and standards. Where is the magical matrix that one can pick his directive and test suite from for a given type of product? Kind Regards, Sam Wismer Engineering Manager ACS, Inc. Phone: (770) 831-8048 Fax: (770) 831-8598 Web: www.acstestlab.com
