Thermocouple alternatives
Yep, infrared point and shoot thermometers have some terrific advantages but
another drawback with 'infra-red' instruments, they are calibrated for one
value of surface emissivity. Before relying on the value for precision
measurements you should familiarize yourself with Emissivity.
Someone mentioned the Shuttle disaster and asked how many unfulfilled warnings
went by before the catastrophe. I've just finished reading a study of the
incident by a social scientist ("The Challenger Launch Decision") who concludes
that, contrary to the findings of the Presidential Commission and NASA reports,
the primary cause was not rule breaking by negligent managers responding to
pressure. There were mistakes, and their origins can be traced back to the
change in values and attitudes following the Apollo Missions ten years before
the Challenger incident.
What bothers me more is the scrapping of the substitute booster program after
investment of about $500M when Congress changed in 93-94. The original design,
made in Utah, is still flying, with all its bugs, because of political
budgetary choices.
Everyone still breathes a sigh of relief when booster separation is complete at
150,000 feet and Mach N. For you engineers out there, each booster weighs 90
tons at burnout. Can you imagine the bang that is felt inside the shuttle at
when the two sets of booster separation solid rocket motors fire
simultaneously? There are sixteen altogether, four at each end of each booster,
and each is a foot in diameter. I can recommend Inside The Space Station DVD
for space enthusiasts. Slow motion the shuttle launch segment and watch the
bend and springback in between main engine ignition and solid booster ignition.
That's what tore the joint open on Challenger, cold O ring couldn't bend fast
enough to seal the gap.
Best Regards
Ted Rook, Console Engineering, ext 4659
Please note our new location and phone numbers:
Crest Audio Inc, 16-00 Pollitt Drive
Fair Lawn, NJ 07410 USA
201 475 4600 telephone receptionist, 8.30 - 5 pm EST.
201 475 4659 direct line w/voice mail, 24 hrs.
201 475 4677 fax, 24 hrs.
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Re: European and North American Cordage
Peter, We used a HARSVT 3x18AWG 1.00mm2 "Universal" linecord from Feller on the Lexmark MarNet XLe External Network Adapter. This had a Harmonized plus UL/CSA-listed cordage. I can't find my Feller catalog right now, and their website (http://www.feller-at.com/ ) doesn't say, but I think that they had HARSVT cordage in 16AWG and 14AWG, along with HARSJT cordage. John Barnes Advisory Engineer Lexmark International --- 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: Comparing EMI test results
We have also performed some experimentation with our compact semi-anechoic chamber (prescan) and OATS, both at 3 meters. Our experience correlates with Doug's. For devices as small as say a shoebox, our correlation is typically within 2 dB. For systems that are 1.5 meters and floor mounted with a few interconnecting cables, our correlation is typically within 4 dB. We have seen an occasional emissions in the chamber that did not show up on the site. As we use a bilog in the chamber and use bicon and log periodic on the site, we did not pursue the "why". I would assume that it is related to the imperfect absorption of the chamber compared to the open space of the OATS. Another part that might make a difference in your measurements is the conditions at each site. Our chamber is a fairly constant 72 degrees, 50% humidity producing a constant NSA. The OATS, however, varies in its moisture content which we have learned contributes to the variation between chamber and OATS. When the site is dry, we get a "down the middle" NSA; when it is soaked, we get closer to the NSA limit and also a larger variation between the chamber and OATS as would be expected. We have not yet discovered why the moisture affects the NSA. On the other hand, the OATS is compliant and we have learned to deal with the "degrees" of variation, so at this point we live with it. Don Umbdenstock > -- > From: Doug McKean[SMTP:dmck...@auspex.com] > Reply To: Doug McKean > Sent: Monday, January 07, 2002 1:44 PM > To: EMC-PSTC Discussion Group > Subject: Re: Comparing EMI test results > > > Not to rain on the parade, but be careful when > comparing semi-anechoic chambers versus OATS > that are of different distances, i.e. 3m vs. 10m. You > may get not only widely different measurements > even when compensating for the distances, but you > may also obtain different frequencies. On two > occasions, I've had frequencies show up rather > prominently in the chamber prescan not to be > seen to any significance at an OATS. > > In other words, to get a fairly reliable comparison > between a chamber and a site, in my opinion, you'll > first have to compare a 10m chamber with a 10m > OATS. Then, work backwards to a 3m chamber. > > You will also have to develop a fudge factor for the > size of the EUT. The size can effect results as well. > You may get good correlation with a small tabletop > EUT and terrible correlation to a much larger device. > Possible reasons for this I'll leave to discussion. But > suffice it to say, the closer the product is to a point > source the better the correlation. The farther the > product is from a point source, the worse the > correlation. At least in my experience. > > Name the site with which you will be getting an > official measurement as your standard, then work > all the others in reference to it. The standard site > will be the one which will have the final say. > > Sorta been there ... > Done that ... etc ... > Sorta gave up. > > - 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: implantable cardiac pacemaker immunity standards
I think I may have given an old reference to pacemaker immunity testing. Looking at the FDA site now shows a lot of developmental work going on to update the AAMI pacemaker standard. Take a look at ANSI / AAMI PC69/2000 at: http://webstore.ansi.org/ansidocstore/ Sorry for the old directions. Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis >-Original Message- >From: Low, Aaron S [mailto:aaron.s@lmco.com] >Sent: Monday, January 07, 2002 8:11 AM >To: emc-p...@majordomo.ieee.org >Subject: implantable cardiac pacemaker immunity standards > > > >Good morning all, > >I would like to know if implantable pacemakers are generally tested to >200V/m field strength levels at RADAR frequencies (~400MHz - >several GHz). >If the designers and producers do, are they required to? > >This information is needed for radiation hazard analyses. > >Thank you > >> Aaron S. Low >>Associate Systems Engineer >> Naval Electronics and Surveillance Systems >> EP5 D5 MD45 Syracuse, NY 13221-4840 >> Phone: (315) 456-1203Fax: (315) 456-0509 >L --- 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.
CE Marking Directive
Looking at the Eur-Lex homepage, it would appear that 93/68 (CE Marking) is still in force. Unfortunately, I could only see the Directive text, which relates mainly to those Directives amended, and not the annexes. Anyone know where I can get/download a copy of the annexes? Thanks, Dave Wilson Senior Compliance Engineer Alidian Networks 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: 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 CE Marking - my mistake
I guess the CE Marking directive doesn't have annexes, rather it amends annexes of other Directives. Advancing age and resultant poor recall. Dave Wilson Senior Compliance Engineer Alidian Networks 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: 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: implantable cardiac pacemaker immunity standards
Aaron: Pacemakers are tested to the FDA MDS-401-xxx. Take a look at the FDA's web site. Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis >-Original Message- >From: Low, Aaron S [mailto:aaron.s@lmco.com] >Sent: Monday, January 07, 2002 8:11 AM >To: emc-p...@majordomo.ieee.org >Subject: implantable cardiac pacemaker immunity standards > > > >Good morning all, > >I would like to know if implantable pacemakers are generally tested to >200V/m field strength levels at RADAR frequencies (~400MHz - >several GHz). >If the designers and producers do, are they required to? > >This information is needed for radiation hazard analyses. > >Thank you > >> Aaron S. Low >>Associate Systems Engineer >> Naval Electronics and Surveillance Systems >> EP5 D5 MD45 Syracuse, NY 13221-4840 >> Phone: (315) 456-1203Fax: (315) 456-0509 >L > > >--- --- 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: Comparing EMI test results
Not to rain on the parade, but be careful when comparing semi-anechoic chambers versus OATS that are of different distances, i.e. 3m vs. 10m. You may get not only widely different measurements even when compensating for the distances, but you may also obtain different frequencies. On two occasions, I've had frequencies show up rather prominently in the chamber prescan not to be seen to any significance at an OATS. In other words, to get a fairly reliable comparison between a chamber and a site, in my opinion, you'll first have to compare a 10m chamber with a 10m OATS. Then, work backwards to a 3m chamber. You will also have to develop a fudge factor for the size of the EUT. The size can effect results as well. You may get good correlation with a small tabletop EUT and terrible correlation to a much larger device. Possible reasons for this I'll leave to discussion. But suffice it to say, the closer the product is to a point source the better the correlation. The farther the product is from a point source, the worse the correlation. At least in my experience. Name the site with which you will be getting an official measurement as your standard, then work all the others in reference to it. The standard site will be the one which will have the final say. Sorta been there ... Done that ... etc ... Sorta gave up. - 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: Thermocouple alternative?
Bonjour again, Looking a little bit longer on the FISO web site I also found this: http://www.fiso.com/page_transfo.htm which describes their next generation in fiber optic direct winding temperature monitoring system for transformers... Regards, == Benoît Nadeau, ing., M.ing. (P.Eng., M.Eng) Gérant du Groupe Conformité (Conformity Group Manager) Matrox == 1055, boul St-Régis Dorval (Québec) Canada H9P 2T4 Tel : (514) 822-6000 (2475) Fax : (514) 822-6275 mailto:bnad...@matrox.com http://www.matrox.com == -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Chris Maxwell Sent: Monday, January 07, 2002 11:20 To: Crabb, John; emc-p...@majordomo.ieee.org Subject: Re: Thermocouple alternative? Hi John, A possible solution would be to use an infrared non-contact thermometer. They measure temperature essentially by pointing them at the object of interest. They have a few drawbacks that I know of: 1. You need to have visual access to the part or surface of interest. 2. You need to account for "spot size" since its detector essentially integrates all of the infrared in its field of view. The spot size changes with distance from the thermometer to the surface of interest. 3. If you are trying to graph temperature over time: you can't just glue it in place and hook it to a data logger. I don't know if it would be worth rigging up some kind of tripod to keep the infrared detector aimed at the point of interest. We had one in the lab for a couple of days. It was a handheld, battery powered unit about the size of a Palm Pilot. Sadly, I only got to play with it a little bit before it was taken away. I wanted to see how accurate it was at measureing component temperatures on a circuitboard. 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: Crabb, John [SMTP:jo...@exchange.scotland.ncr.com] > Sent: Monday, January 07, 2002 9:02 AM > To: emc-p...@majordomo.ieee.org > Subject: RE: EMC-related safety issues > > Seeing that we have got round to the subject of thermocouples, etc, I > often > use a Solartron SI3535D datalogger with thermocouples for measuring > component temperatures, and find quite often that it does not give > "correct" > readings when thermocouples are placed on transformers in switching > power supplies, high voltage transformers in monitors, etc. I can get > a > "correct" reading by switching off the EUT momentarily, obviously > removing the source of the problem. Note that the problem can occur > even if the thermocouple is not making an electrical connection to the > component winding involved. > > Any suggestions how to overcome this ? My previous antique datalogger > didn't have this problem, but it eventually had to be scrapped due to > lack > of spare parts - and the expectation that a more modern unit would be > better !. > > Regards, > John Crabb, Development Excellence (Product Safety) , > NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. > DD2 3XX > E-Mail :john.cr...@scotland.ncr.com > Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. > VoicePlus 6-341-2289. --- 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
RE: Thermocouple alternative?
Bonjour de Montreal, >From an earlier life in a commercial EMC testing lab, I had one day this customer from Quebec City who developped a Fiber-optic based temperature sensing system. Their web site specifies that it is immune to RF. I think it is worth to look at: http://www.fiso.com/temp.htm Best regards, == Benoît Nadeau, ing., M.ing. (P.Eng., M.Eng) Gérant du Groupe Conformité (Conformity Group Manager) Matrox == 1055, boul St-Régis Dorval (Québec) Canada H9P 2T4 Tel : (514) 822-6000 (2475) Fax : (514) 822-6275 mailto:bnad...@matrox.com http://www.matrox.com == -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Doug Powell Sent: Monday, January 07, 2002 12:32 To: emc-p...@majordomo.ieee.org Subject: Re: Thermocouple alternative? John, In my company, I often run into this problem and a non-contact or infrared thermometer is not always pratical. Like you, I also had to resort to momentary turn off to get accurate readings. In one instance, I had magentic fields strong enough to cause damage to the instrument. There are several things you can do and not all of these are always necessary. 1) I exclusively use "T" type thermocouple wire because it has no ferrous content and the effective temperature range more closely "brackets" the temperatures I am interested in. The reason for non-ferrous wire is strong magnetic fields not only induce erroneous readings, but they also cause heating of the thermocouple itself. In the past I typically saw this problem with the "K" & "J" types. Simply doing a momentary turn-off does not correct this problem as the wire takes some descrete time to cool off and after a point you don't know if you device under test is cooling as well. The problem is that I've never found a handheld meter that accepts "T" type wire. 2) The next thing I do is insure the thermocouple conductors are not separated, keeping loop area small. Twisting is ideal if you can do this without damaging to the welded tip. Ideally you should be able to weld your own. 3) If possible, try to orient thermocouple wires to avoid 'cutting' flux lines. 4) Try using ferrite beads to knock down any common-mode RF induced on the wire and being conducted into the instrument. The readings you are interested in are essentially DC. 5) If you are still having troubles, construct a Faraday shield by wrapping with copper foil. Grounding the shield may be helpful. The shield needs to fully enclose the thermocouple bead and surround the wires for some distance, far enough to exit the area where the fields are. Be sure the copper foil is insulated inside and out. Note, readings may take a little longer. 6) Finally, if all else fails, you can resort to the resistance method described in IEC 61558-1 (fomerly IEC 60742) clause 14.2. This takes a milli-Ohm meter. -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. [quote]Hi John, A possible solution would be to use an infrared non-contact thermometer. They measure temperature essentially by pointing them at the object of interest. They have a few drawbacks that I know of: 1. You need to have visual access to the part or surface of interest. 2. You need to account for "spot size" since its detector essentially integrates all of the infrared in its field of view. The spot size changes with distance from the thermometer to the surface of interest. 3. If you are trying to graph temperature over time: you can't just glue it in place and hook it to a data logger. I don't know if it would be worth rigging up some kind of tripod to keep the infrared detector aimed at the point of interest. We had one in the lab for a couple of days. It was a handheld, battery powered unit about the size of a Palm Pilot. Sadly, I only got to play with it a little bit before it was taken away. I wanted to see how accurate it was at measureing component temperatures on a circuitboard. 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: Crabb, John [SMTP:jo...@exchange.scotland.ncr.com] > Sent: Monday, January 07, 2002 9:02 AM > To: emc-p...@majordomo.ieee.org > Subject: RE: EMC-related safety issues > > Seeing that we have got round to the subject of thermocouples, etc, I > often > use a Solartron SI3535D datalogger with thermocouples for measuring > component temperatures, and find quite often that it does not give > "correct" > readings when thermocouples are placed on transformers in switching > power supplies, high voltage transformers in monitors, etc. I can get > a > "correct" r
Re: EMC-related safety issues
I read in !emc-pstc that Crabb, John wrote (in ) about 'EMC-related safety issues', on Mon, 7 Jan 2002: >Any suggestions how to overcome this ? My previous antique datalogger >didn't have this problem, but it eventually had to be scrapped due to lack >of spare parts - and the expectation that a more modern unit would be >better !. AS Gert Gremmen says, this problem is pretty fundamental. Maybe the only solution is to use resistive temperature sensors instead, such as precision thermistors. -- 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.
FW: Thermocouple alternative?
-Original Message- From: Chris Maxwell [mailto:chris.maxw...@nettest.com] Sent: Monday, January 07, 2002 9:20 AM To: Crabb, John; emc-p...@majordomo.ieee.org Subject: Re: Thermocouple alternative? John, We use T-type thermocouples which are not as ferrous as J and K types, and therefore not as susceptible to electromagnetic fields. Still, we run into problems (we make high-power switching power supplies, by the way). Sometimes noise is coupled into the thermocouple wire. I have fixed this with a choke in the past. I have had difficulty convincing agencies to accept data from non-contact thermal measurement systems, e.g., infrared or optical. The way that I have convinced them is to take side-by-side measurements on something that is not producing strong fields using a thermocouple and the non-contact measuring device. When they saw that the two devices measured the same temperature, they were satisfied. Good Luck, Jeff Jenkins Advanced Energy Industries, Inc. Fort Collins, CO > -Original Message- > From: Crabb, John [SMTP:jo...@exchange.scotland.ncr.com] > Sent: Monday, January 07, 2002 9:02 AM > To: emc-p...@majordomo.ieee.org > Subject: RE: EMC-related safety issues > > Seeing that we have got round to the subject of thermocouples, etc, I > often > use a Solartron SI3535D datalogger with thermocouples for measuring > component temperatures, and find quite often that it does not give > "correct" > readings when thermocouples are placed on transformers in switching > power supplies, high voltage transformers in monitors, etc. I can get > a > "correct" reading by switching off the EUT momentarily, obviously > removing the source of the problem. Note that the problem can occur > even if the thermocouple is not making an electrical connection to the > component winding involved. > > Any suggestions how to overcome this ? My previous antique datalogger > didn't have this problem, but it eventually had to be scrapped due to > lack > of spare parts - and the expectation that a more modern unit would be > better !. > > Regards, > John Crabb, Development Excellence (Product Safety) , > NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. > DD2 3XX > E-Mail :john.cr...@scotland.ncr.com > Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. > VoicePlus 6-341-2289. --- 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, 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: 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: Thermocouple alternative?
John, In my company, I often run into this problem and a non-contact or infrared thermometer is not always pratical. Like you, I also had to resort to momentary turn off to get accurate readings. In one instance, I had magentic fields strong enough to cause damage to the instrument. There are several things you can do and not all of these are always necessary. 1) I exclusively use "T" type thermocouple wire because it has no ferrous content and the effective temperature range more closely "brackets" the temperatures I am interested in. The reason for non-ferrous wire is strong magnetic fields not only induce erroneous readings, but they also cause heating of the thermocouple itself. In the past I typically saw this problem with the "K" & "J" types. Simply doing a momentary turn-off does not correct this problem as the wire takes some descrete time to cool off and after a point you don't know if you device under test is cooling as well. The problem is that I've never found a handheld meter that accepts "T" type wire. 2) The next thing I do is insure the thermocouple conductors are not separated, keeping loop area small. Twisting is ideal if you can do this without damaging to the welded tip. Ideally you should be able to weld your own. 3) If possible, try to orient thermocouple wires to avoid 'cutting' flux lines. 4) Try using ferrite beads to knock down any common-mode RF induced on the wire and being conducted into the instrument. The readings you are interested in are essentially DC. 5) If you are still having troubles, construct a Faraday shield by wrapping with copper foil. Grounding the shield may be helpful. The shield needs to fully enclose the thermocouple bead and surround the wires for some distance, far enough to exit the area where the fields are. Be sure the copper foil is insulated inside and out. Note, readings may take a little longer. 6) Finally, if all else fails, you can resort to the resistance method described in IEC 61558-1 (fomerly IEC 60742) clause 14.2. This takes a milli-Ohm meter. -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. [quote]Hi John, A possible solution would be to use an infrared non-contact thermometer. They measure temperature essentially by pointing them at the object of interest. They have a few drawbacks that I know of: 1. You need to have visual access to the part or surface of interest. 2. You need to account for "spot size" since its detector essentially integrates all of the infrared in its field of view. The spot size changes with distance from the thermometer to the surface of interest. 3. If you are trying to graph temperature over time: you can't just glue it in place and hook it to a data logger. I don't know if it would be worth rigging up some kind of tripod to keep the infrared detector aimed at the point of interest. We had one in the lab for a couple of days. It was a handheld, battery powered unit about the size of a Palm Pilot. Sadly, I only got to play with it a little bit before it was taken away. I wanted to see how accurate it was at measureing component temperatures on a circuitboard. 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: Crabb, John [SMTP:jo...@exchange.scotland.ncr.com] > Sent: Monday, January 07, 2002 9:02 AM > To: emc-p...@majordomo.ieee.org > Subject: RE: EMC-related safety issues > > Seeing that we have got round to the subject of thermocouples, etc, I > often > use a Solartron SI3535D datalogger with thermocouples for measuring > component temperatures, and find quite often that it does not give > "correct" > readings when thermocouples are placed on transformers in switching > power supplies, high voltage transformers in monitors, etc. I can get > a > "correct" reading by switching off the EUT momentarily, obviously > removing the source of the problem. Note that the problem can occur > even if the thermocouple is not making an electrical connection to the > component winding involved. > > Any suggestions how to overcome this ? My previous antique datalogger > didn't have this problem, but it eventually had to be scrapped due to > lack > of spare parts - and the expectation that a more modern unit would be > better !. > > Regards, > John Crabb, Development Excellence (Product Safety) , > NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. > DD2 3XX > E-Mail :john.cr...@scotland.ncr.com > Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. > VoicePlus 6-341-2289. [/quote] Replies to this message may be posted in a public forum. --- This message is from the IEEE EMC Society Product Safety Technical Commit
RE: Comparing EMI test results
I agree absolutely with Brent. Also, even if ALL the other variables are STRICTLY controlled you could conciveably get as much as 8 db variation between sites. I suggest ( as Brent has already done) getting Lowell Kolbs paper on site comparisons. From: "Brent DeWitt" Reply-To: "Brent DeWitt" To: "Rao, Praveen" , Subject: RE: Comparing EMI test results Date: Sun, 6 Jan 2002 22:46:22 -0700 Rao, The comb generator is not a bad choice, but a few things should be checked (yes, I've done this). First, establish the base variation in the source. No antenna, just a direct connection to the receiver/SA that you will use for the evaluation under an expected, reasonable variation in temperature and battery condition. Take enough samples over enough days to make yourself statistically comfortable with the level of uncertainty you're targeting. Second, use the volumetric calibration procedure (as required for "alternative" test facilities) on both the SAC _and_ the OATS. Having done volumetric NSAs on high quality SACs and low quality OATS, I can say there is _no_ reason the OATS can be considered a "gold standard" in all instances. Lowell Kolb of Hewlett-Packard did an excellent paper on comparison of OATS sites a few years back. I would suggest looking up his paper for an idea of OATS site to site variation. Lastly, everything I've just said will, most likely, be totally swamped by variations in the EUT setup under "real" EUT testing unless you can _strictly_ control them. Don't go there. The more "real" the simulated EUT becomes, the more variables you introduce into the site evaluation. As more variables are introduced, the greater the number of data points will be required to resolve the result. While it is obvious to the most casual observer that the simple comb generator does not represent a "real" EUT, it does represent a single frequency component at a single phase component for each of the volumetric measurement points. The best work done in this area has used a VNA for evaluation of both quantities, but from the literature, this would appear to be most useful in diagnostic applications. Empirically, if the magnitude of the seven single planar volumetric points looks good, the site is _probably_ pretty good. Of course, if the SA is systematically off at all points, check the antenna calibration! Best regards, Brent DeWitt -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Rao, Praveen Sent: Sunday, January 06, 2002 6:16 PM To: emc-p...@majordomo.ieee.org Subject: Comparing EMI test results I'm trying to setup a programme to compare test results (for Radiated Emissions) between test labs. The plan is to circulate a "Artifact" around the labs and compare the results. The test sites being compared are Semi-anechoic Chambers v/s OATS. The source used is a wideband "RF comb generator". I would like to understand the concept fully before I initiate this programme. Is there any information readily available on this topic? Any help will be greatly appreciated. Thanks. Praveen --- 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. _ Send and receive Hotmail on your mobile device: http://mobile.msn.com --- This message is from the IEEE EMC Society Product Safety Technical Com
Re: Thermocouple alternative?
Hi John, A possible solution would be to use an infrared non-contact thermometer. They measure temperature essentially by pointing them at the object of interest. They have a few drawbacks that I know of: 1. You need to have visual access to the part or surface of interest. 2. You need to account for "spot size" since its detector essentially integrates all of the infrared in its field of view. The spot size changes with distance from the thermometer to the surface of interest. 3. If you are trying to graph temperature over time: you can't just glue it in place and hook it to a data logger. I don't know if it would be worth rigging up some kind of tripod to keep the infrared detector aimed at the point of interest. We had one in the lab for a couple of days. It was a handheld, battery powered unit about the size of a Palm Pilot. Sadly, I only got to play with it a little bit before it was taken away. I wanted to see how accurate it was at measureing component temperatures on a circuitboard. 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: Crabb, John [SMTP:jo...@exchange.scotland.ncr.com] > Sent: Monday, January 07, 2002 9:02 AM > To: emc-p...@majordomo.ieee.org > Subject: RE: EMC-related safety issues > > Seeing that we have got round to the subject of thermocouples, etc, I > often > use a Solartron SI3535D datalogger with thermocouples for measuring > component temperatures, and find quite often that it does not give > "correct" > readings when thermocouples are placed on transformers in switching > power supplies, high voltage transformers in monitors, etc. I can get > a > "correct" reading by switching off the EUT momentarily, obviously > removing the source of the problem. Note that the problem can occur > even if the thermocouple is not making an electrical connection to the > component winding involved. > > Any suggestions how to overcome this ? My previous antique datalogger > didn't have this problem, but it eventually had to be scrapped due to > lack > of spare parts - and the expectation that a more modern unit would be > better !. > > Regards, > John Crabb, Development Excellence (Product Safety) , > NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. > DD2 3XX > E-Mail :john.cr...@scotland.ncr.com > Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. > VoicePlus 6-341-2289. --- 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.
implantable cardiac pacemaker immunity standards
Good morning all, I would like to know if implantable pacemakers are generally tested to 200V/m field strength levels at RADAR frequencies (~400MHz - several GHz). If the designers and producers do, are they required to? This information is needed for radiation hazard analyses. Thank you > Aaron S. Low >Associate Systems Engineer > Naval Electronics and Surveillance Systems > EP5 D5 MD45 Syracuse, NY 13221-4840 > Phone: (315) 456-1203Fax: (315) 456-0509 L --- 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 and North American Cordage
Peter I remember this too - I think it was an Austrian/German company (possibly Feller). However, be warned, that I also seem to remember that the cordage was dual certified only as part of extension cordsets with male and female IEC60320 couplers on the ends (e.g. as used with many PC's) - not for use as actual flexible mains cords with wall-socket plugs on the supply end. John Allen -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: 07 January 2002 10:14 To: "EMC-PSTC (E-mail)" < Subject: European and North American Cordage Dear All, I remember a power cordage supplied by a manufacturer which had European and North American approvals. Does anyone know the manufacturer and type of cordage? 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. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: + 972-(0)3-5339022 Fax: + 972-(0)3-5339019 Mobile: + 972-(0)54-838175 --- 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.
Human Exposure to EMF
Please contact me off line if you are a user of commercial software that models induced body currents or SAR from exposure to electromagnetic fields. My interest is in the frequency range of 50 Hz to 30 MHz. Richard Woods Sensormatic Electronics Tyco International --- 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: Comparing EMI test results
Have the evaluation performed at both 3 meters and 10 meters. Should be interesting to see the results. John Shinn -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Rao, Praveen Sent: Sunday, January 06, 2002 7:14 PM To: Ken Javor; emc-p...@majordomo.ieee.org Subject: RE: Comparing EMI test results Thanks for the response. The purpose is to test both, the facility (semi-anechoic v/s OATS) and the quality of results. The comb generator is my first approach. A standard test sample(with cables) will follow. Any procedures, data, results, experience on this issue ? -Original Message- From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Monday, 7 January 2002 13:47 To: Rao, Praveen; emc-p...@majordomo.ieee.org Subject: Re: Comparing EMI test results Whether a comb generator is a good artifact depends somewhat on what your purpose is. If your purpose is to check how well calibrated the site is I think a comb generator is an excellent artifact because it is physically small and should generate the same radiation pattern at all facilities. But if your purpose is to check the "quality" of the testing done at different facilities including how good the test personnel are, then I believe you need a device with attached cables, since maximizing emissions will then involve not only height searches, but also rotation of the turntable and movement of the attached cables. Maybe you can attach a cable or two to the rf jack that normally seats the stub. on 1/6/02 8:16 PM, Rao, Praveen at praveen@fujitsu.com.au wrote: > > > > I'm trying to setup a programme to compare test results (for > Radiated Emissions) between test labs. The plan is to circulate a > "Artifact" around the labs and compare the results. The test sites being > compared are Semi-anechoic Chambers v/s OATS. The source used is a > wideband "RF comb generator". I would like to understand the concept > fully before I initiate this programme. Is there any information readily > available on this topic? Any help will be greatly appreciated. Thanks. > Praveen > > > > --- > 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. --- 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 richwo...@tycoint.com wrote (in <846BF526A205F8 4BA2B6045BBF7E9A6ABC4FEA@flbocexu05>) about 'EMC-related safety issues', on Mon, 7 Jan 2002: >John, I have to disagree with your statement, "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." > >If this is true, how do you explain the fact that the Alarm Systems immunity >standard EN 50130-4 requires a higher immunity levels and that, per clause >6, the acceptance criteria is per the requirements of a CENELEC performance >standard if it is published - e.g. EN 50132-2-1 (CCTV cameras), EN50132-4-1 >(Access Control). This certainly appears to be safety related. I was referring to the Generic and Basic Standards. But the cases you cite are related to *false alarms* or the opposite, i.e. purely system malfunction. Insofar as the standards apply to fire alarms and/or social alarms, safety-of-life is a consequent issue. AFAIK, none of those more stringent limits was determined according to the principles specified in IEC61508. -- 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
Regarding the snip below. The fact that it is a radio that is the victim is still the salient factor here. The emissions in close to the lamp are higher than at three meters, but only enough higher to affect a radio, nothing else. Regarding the thermocouple based incubator issue (sensitivity on the order of uV). If the sensitivity is truly at the level of uV, then yes this device could respond to lower level emissions, IF the pickup mechanism were of the same efficiency as a radio antenna. If it is not, and they actually took some pains to shield the wiring, then it should have a little more immunity. But I said before, and I don't believe was rebutted on this, that if the device was susceptible at or near CISPR22/FCC limits, then it should never have worked from the get-go, as anyone who has ever made measurements on an OATS would understand. 1/7/02 6:49 AM, cherryclo...@aol.com at cherryclo...@aol.com wrote: Secondly maybe when you wrote the above you weren't thinking of the previous correspondence in this thread about the proximity of the low-energy lamp to a bedside radio. Yes, I know, this concerned a radio receiver, what I mean to draw your attention to is the discussion about the intention and validity of the EMC standards they simply do not cover situations where devices are placed close to each other so they cannot be relied upon to provide compatibility in such situations. Military EMC standards are more thorough in this respect.
RE: CEN Standards free on-line
Before we start cutting our budgets for the purchase of standards, I read in another CEN announcement ; "eEurope standards are defined in workshops whose agreements will be made available for downloading free of charge from the CEN web site". So it may just be CEN Workshop Agreements (CWAs) that are available for free. These seem to be rather unique documents. To quote from BSI Update Standards "A CEN Workshop agreement (CWA) represents only the concensus of those who participated in the parent CEN Workshop; hence, a CWA may not represent the views of all interested parties and so is not accorded the status of a European standard. The solutions offered through a CWA may compete with those offered in another CWA in the same field or a related European standard." Regards, John Crabb, Development Excellence (Product Safety) , NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. DD2 3XX E-Mail :john.cr...@scotland.ncr.com Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. VoicePlus 6-341-2289. -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: 04 January 2002 13:40 To: emc-p...@majordomo.ieee.org Subject: RE: CEN Standards free on-line For those of you having difficulty with the link - the link overflowed onto the next line. You will have to paste it back together to obtain the full and correct link. And John is correct. Someone forget to tell the CEN website that the documents are now free. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Friday, January 04, 2002 1:39 AM To: emc-p...@majordomo.ieee.org Subject: Re: CEN Standards free on-line I read in !emc-pstc that richwo...@tycoint.com wrote (in <846BF526A205F8 4BA2B6045BBF7E9A6ABC4FDD@flbocexu05>) about 'CEN Standards free on- line', on Thu, 3 Jan 2002: >According to this press release, CEN standards should now be on line for >free. > >http://europa.eu.int/rapid/start/cgi/guesten.ksh?p_action.gettxt=gt&doc=IP/ 0 >1/1837|0|RAPID&lg=EN It does indeed say that, BUT the CEN web page itself still refers one to national standards bodies for purchasing the standards! No mention at all of any free downloads! -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.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.
RE: EMC-related safety issues
Yes, Gert, there is a fine line. The alarm systems standards are written around performance. It would be highly unlikely that the failure of a CCTV camera to comply with the increased immunity standards would create a physical hazard from the camera itself. Rather, failure of the camera to perform as intented might result in an hazard caused by external conditions that occur undetected (e.g., fire, robbery, intrusion, etc). Richard Woods Sensormatic Electronics Tyco International -Original Message- From: CE-TEST [mailto:cet...@cetest.nl] Sent: Monday, January 07, 2002 9:13 AM To: richwo...@tycoint.com; emc-p...@majordomo.ieee.org Subject: RE: EMC-related safety issues Hi Richard, Group I agree that those requirements look safety related, but they are strictly functional. The difference is subtle: As this standard is concerned with equipment used for safety purposes, the requirements are thus safety related in THAT sense, but not in the sense of equipment's safety or safety risks CAUSED by using the equipment. These are not considered, althouigh testin according to EN 50130 may contribute to increased product safety. Most safety topics can be found in LVD related standards, such as EN 60730 (not for EN 50130 equipment). Many LVD standards are not very elaborate about EM Safety, and directly point to a deviation of the Generic standards. I might say that "EM and safety of equipment" is an area that is completely unexplored. (i do not use the abbreviation EMC as this topic is not about compatibility. I should use EMS (afety) but this abbreviation has already been taken...) Gert Gremmen -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of richwo...@tycoint.com Sent: maandag 7 januari 2002 14:13 To: emc-p...@majordomo.ieee.org Subject: RE: EMC-related safety issues John, I have to disagree with your statement, "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." If this is true, how do you explain the fact that the Alarm Systems immunity standard EN 50130-4 requires a higher immunity levels and that, per clause 6, the acceptance criteria is per the requirements of a CENELEC performance standard if it is published - e.g. EN 50132-2-1 (CCTV cameras), EN50132-4-1 (Access Control). This certainly appears to be safety related. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Friday, January 04, 2002 11:49 AM To: emc-p...@majordomo.ieee.org Subject: Re: EMC-related safety issues 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 immuni
RE: EMC-related safety issues
In addition, the junction of any thermocouple is an inherent AC rectifier that is out of control by the designer. Any impedance unbalance between the two thermocouple wires (including the PCB and OPAMP) will cause current to flow in the thermocouple junction and give rise to (large errors) I personally found error from 120 degrees Kelvin at room temperature using thermocouple meters for the process industry. This inherent sensitivity of thermocouples disqualifies most designs for reliability purposes. Gert Gremmen ce-test, qualified testing http://www.cetest.nl -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of cherryclo...@aol.com Sent: maandag 7 januari 2002 12:49 To: ken.ja...@emccompliance.com Cc: emc-p...@majordomo.ieee.org Subject: Re: EMC-related safety issues Sorry everyone! When I replied yesterday to Ken's posting I didn't spot an error he had made. He had assumed an incubator compliant to 1V/m close to a laptop, whereas the question I originally posed concerned an incubator such as the one I had tested that had full-scale temperature errors at 1V/m from 30 to 1000MHz. So I hope you'll all forgive me if I redo part of my reply. Here goes... Ken said (06/01/02 06:56:46 GMT Standard Time)... Would I feel comfortable placing a CISPR compliant PC next to a medical device qualified to 1 V/m? There is an inherent (not planned) margin of safety here that is many orders of magnitude. The answer is absolutely yes. If there were a problem, I would expect it more to occur below 30 MHz, at the power supply switching frequency, IF the medical device processed extremely low levels of electrical signals and was poorly shielded. But I believe there are separate immunity requirements which cover this eventuality as well. Firstly – my original question concerned how close one would be prepared to place a fully-compliant laptop to the unmodified incubator, which as you will recall I found to give full-scale temperature errors at 1V/m field strengths from 30 to 1000MHz. An incubator that was qualified to 1V/m (as per Ken's reply above) would be at least 28dB less sensitive to RF fields (assuming a square-law relationship for error voltage versus field strength) and would be much more robust. In the EU such medical devices are expected to work properly in fields of at least 3V/m (you can't rely on the CE mark as any guarantee), but I posed the question about the unmodified incubator because I understand that outside of the EU few countries have mandatory immunity regulations. Note that thermocouples have an output of between 3 and 50 uV/degreeC, so if you want to achieve ±0.1C accuracy you are looking to keep error voltages below 0.3 to 5uV. It doesn't take much RF ingress to cause that level of error. Note also that traditional thermocouple amplifier design (such as commonly seen in the 1960s and 1970s, and still lingering on in some products) brings the thermocouple wires straight into an opamp. No shielding, no filtering, and no CMR in the opamp at RF. Worst-case RF demodulation performance is almost a certainty with such a design. Many other 'traditional' transducers using microvolt signal levels used to use amplifiers designed just as badly for EMC, and I sincerely hope there are none of them left any more. Aside: A typical comment from a UK EMC test lab manager (this one from a personal communication in 1998): "I was testing a temperature control system for immunity yesterday. As usual, I found that I could get any temperature I wanted simply by varying the RF frequency." Just so you don't think my incubator example was a one-off. Secondly – maybe when you wrote the above you weren't thinking of the previous correspondence in this thread about the proximity of the low-energy lamp to a bedside radio. Yes, I know, this concerned a radio receiver, what I mean to draw your attention to is the discussion about the intention and validity of the EMC standards – they simply do not cover situations where devices are placed close to each other – so they cannot be relied upon to provide compatibility in such situations. Military EMC standards are more thorough in this respect. And as I have already said, commercial EMC standards were not written with safety issues in mind, and most safety standards have not been written with EMC-related issues in mind (see my IEEE 2001 EMC Symposium paper and my longer article in ITEM UPDATE 2001 for details). Regards again, Keith Armstrong In a message dated 06/01/02 15:51:27 GMT Standard Time, cherryclo...@aol.com writes: Subj:Re: EMC-related safety issues Date:06/01/02 15:51:27 GMT Standard Time From:cherryclo...@aol.com Sender:owner-emc-p...@majordomo.ieee.org Reply-to: cherryclo...@aol.com To:ken.ja...@emccompliance.com CC:
RE: EMC-related safety issues
Hi Richard, Group I agree that those requirements look safety related, but they are strictly functional. The difference is subtle: As this standard is concerned with equipment used for safety purposes, the requirements are thus safety related in THAT sense, but not in the sense of equipment's safety or safety risks CAUSED by using the equipment. These are not considered, althouigh testin according to EN 50130 may contribute to increased product safety. Most safety topics can be found in LVD related standards, such as EN 60730 (not for EN 50130 equipment). Many LVD standards are not very elaborate about EM Safety, and directly point to a deviation of the Generic standards. I might say that "EM and safety of equipment" is an area that is completely unexplored. (i do not use the abbreviation EMC as this topic is not about compatibility. I should use EMS (afety) but this abbreviation has already been taken...) Gert Gremmen -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of richwo...@tycoint.com Sent: maandag 7 januari 2002 14:13 To: emc-p...@majordomo.ieee.org Subject: RE: EMC-related safety issues John, I have to disagree with your statement, "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." If this is true, how do you explain the fact that the Alarm Systems immunity standard EN 50130-4 requires a higher immunity levels and that, per clause 6, the acceptance criteria is per the requirements of a CENELEC performance standard if it is published - e.g. EN 50132-2-1 (CCTV cameras), EN50132-4-1 (Access Control). This certainly appears to be safety related. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Friday, January 04, 2002 11:49 AM To: emc-p...@majordomo.ieee.org Subject: Re: EMC-related safety issues 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
RE: EMC-related safety issues
Seeing that we have got round to the subject of thermocouples, etc, I often use a Solartron SI3535D datalogger with thermocouples for measuring component temperatures, and find quite often that it does not give "correct" readings when thermocouples are placed on transformers in switching power supplies, high voltage transformers in monitors, etc. I can get a "correct" reading by switching off the EUT momentarily, obviously removing the source of the problem. Note that the problem can occur even if the thermocouple is not making an electrical connection to the component winding involved. Any suggestions how to overcome this ? My previous antique datalogger didn't have this problem, but it eventually had to be scrapped due to lack of spare parts - and the expectation that a more modern unit would be better !. Regards, John Crabb, Development Excellence (Product Safety) , NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. DD2 3XX E-Mail :john.cr...@scotland.ncr.com Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. VoicePlus 6-341-2289.
Re: European and North American Cordage
Peter, Try keyword searches through Websites http://directories.csa-international.org/ and http://www.ul.com/database/menu2.htm Regards,Paul J. Smith, Teradyne, Boston Peter Merguerian @majordomo.ieee.org on 01/07/2002 05:14:16 AM Please respond to Peter Merguerian Sent by: owner-emc-p...@majordomo.ieee.org To: "\"EMC-PSTC (E-mail)\" <" cc: Subject: European and North American Cordage Dear All, I remember a power cordage supplied by a manufacturer which had European and North American approvals. Does anyone know the manufacturer and type of cordage? 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. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: + 972-(0)3-5339022 Fax: + 972-(0)3-5339019 Mobile: + 972-(0)54-838175 --- 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 for cardio : wich standard apply?
Hi Paolo, I need more information about where your product will be sold. Will it be sold in Europe (CE marking)? There will be some inconsistencies until the part 2 standards have been updated. In the meantime, if a part 2 standard used a dated reference to the 1st edition (1993) of 60601-1-2 then you may use that edition until it has been updated. 60601-2-25 +A1 uses a dated reference to 60601-1-2 (1993), see subclause 1.3. The emc requirements of 2-25 were drafted form an early draft of the 2nd edition of 60601-1-2 so you will notice a similarity in the requirements. You will not go wrong by using the 2nd edition but you may not be required to do so until 1 November 2004. Best regards, Jim -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Paolo Peruzzi Sent: Thursday, January 03, 2002 8:15 AM To: emc-p...@majordomo.ieee.org Subject: EMC for cardio : wich standard apply? hello, I have to test an electrocardiograph for EMC , but I'm in trouble with the standard to apply. There is IEC 60601-2-25 -A1, "Particular requirements for the safety of elecrocardiographs", that deals with EMC, and refers to IEC 60601-1-2 1st ed.(1993, now superseded) and is still valid, as far as I know. But now we have the new edition of IEC 60601-1-2, and its requirements are very different from 60601-2-25-A1 ones. The old edition is replaced by the new one, but what about those particular standards based on it? So I don't know which standard I have to apply. Can anybody out of there dispel my doubts? Best regards p.p. - ESAOTE S.p.A. Paolo Peruzzi Research & Product DevelopmentDesign Quality Control Via di Caciolle,15tel:+39.055.4229306 I- 50127 Florence fax:+39.055.4223305 e-mail: paolo.peru...@esaote.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: 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
John, I have to disagree with your statement, "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." If this is true, how do you explain the fact that the Alarm Systems immunity standard EN 50130-4 requires a higher immunity levels and that, per clause 6, the acceptance criteria is per the requirements of a CENELEC performance standard if it is published - e.g. EN 50132-2-1 (CCTV cameras), EN50132-4-1 (Access Control). This certainly appears to be safety related. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Friday, January 04, 2002 11:49 AM To: emc-p...@majordomo.ieee.org Subject: Re: EMC-related safety issues 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 is only 10^-3. Bit risky, that! If the above reasoning seems flawed, consider a specific case, a lottery with 2000 tickets, numbered to 1999. One person can buy up to 5 tickets, and all tickets are sold. Consider the probability of a 'remarkable occurrence'. This might be the drawing of the number '' or '' or '1234' or even '1010', depending on what you think is 'remarkable'. OK, we already have a cumulative probability down from 1 in 2000 to 1 in 667 or 1 in 500. Now add in the probability that a participant in the lottery is chosen at random to draw the winning number, and draws (one of) his or her own numbers .. You shouldn't be able to get very long odds on a 'remarkable occurrence'! -- 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 y
Re: European and North American Cordage
Peter Try Interpower at the following link. A wide range of cordage with various harmonized and country specific approvals. Also an incredibly helpful technical support desk to aid you in selecting the most suitable product. http://www.interpower.com/ Peter Merguerian wrote: > Dear All, > > I remember a power cordage supplied by a manufacturer which had European and > North American approvals. Does anyone know the manufacturer and type of > cordage? > > 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. > 26 Hacharoshet St., POB 211 > Or Yehuda 60251, Israel > Tel: + 972-(0)3-5339022 Fax: + 972-(0)3-5339019 > Mobile: + 972-(0)54-838175 > > --- > 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 - Senior Compliance 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: EMC-related safety issues
Dear all I have to retire from this correspondence for a few days. I look forward to reading what you have all decided by the end of the week. Regards, Keith Armstrong
Re: EMC-related safety issues
Sorry everyone! When I replied yesterday to Ken's posting I didn't spot an error he had made. He had assumed an incubator compliant to 1V/m close to a laptop, whereas the question I originally posed concerned an incubator such as the one I had tested that had full-scale temperature errors at 1V/m from 30 to 1000MHz. So I hope you'll all forgive me if I redo part of my reply. Here goes... Ken said (06/01/02 06:56:46 GMT Standard Time)... > Would I feel comfortable placing a CISPR compliant PC next to a medical > device qualified to 1 V/m? There is an inherent (not planned) margin of > safety here that is many orders of magnitude. The answer is absolutely > yes. If there were a problem, I would expect it more to occur below 30 > MHz, at the power supply switching frequency, IF the medical device > processed extremely low levels of electrical signals and was poorly > shielded. But I believe there are separate immunity requirements which > cover this eventuality as well. > Firstly – my original question concerned how close one would be prepared to place a fully-compliant laptop to the unmodified incubator, which as you will recall I found to give full-scale temperature errors at 1V/m field strengths from 30 to 1000MHz. An incubator that was qualified to 1V/m (as per Ken's reply above) would be at least 28dB less sensitive to RF fields (assuming a square-law relationship for error voltage versus field strength) and would be much more robust. In the EU such medical devices are expected to work properly in fields of at least 3V/m (you can't rely on the CE mark as any guarantee), but I posed the question about the unmodified incubator because I understand that outside of the EU few countries have mandatory immunity regulations. Note that thermocouples have an output of between 3 and 50 uV/degreeC, so if you want to achieve ±0.1C accuracy you are looking to keep error voltages below 0.3 to 5uV. It doesn't take much RF ingress to cause that level of error. Note also that traditional thermocouple amplifier design (such as commonly seen in the 1960s and 1970s, and still lingering on in some products) brings the thermocouple wires straight into an opamp. No shielding, no filtering, and no CMR in the opamp at RF. Worst-case RF demodulation performance is almost a certainty with such a design. Many other 'traditional' transducers using microvolt signal levels used to use amplifiers designed just as badly for EMC, and I sincerely hope there are none of them left any more. Aside: A typical comment from a UK EMC test lab manager (this one from a personal communication in 1998): "I was testing a temperature control system for immunity yesterday. As usual, I found that I could get any temperature I wanted simply by varying the RF frequency." Just so you don't think my incubator example was a one-off. Secondly – maybe when you wrote the above you weren't thinking of the previous correspondence in this thread about the proximity of the low-energy lamp to a bedside radio. Yes, I know, this concerned a radio receiver, what I mean to draw your attention to is the discussion about the intention and validity of the EMC standards – they simply do not cover situations where devices are placed close to each other – so they cannot be relied upon to provide compatibility in such situations. Military EMC standards are more thorough in this respect. And as I have already said, commercial EMC standards were not written with safety issues in mind, and most safety standards have not been written with EMC-related issues in mind (see my IEEE 2001 EMC Symposium paper and my longer article in ITEM UPDATE 2001 for details). Regards again, Keith Armstrong In a message dated 06/01/02 15:51:27 GMT Standard Time, cherryclo...@aol.com writes: > Subj:Re: EMC-related safety issues > Date:06/01/02 15:51:27 GMT Standard Time > From:cherryclo...@aol.com > Sender:owner-emc-p...@majordomo.ieee.org > Reply-to: mailto:cherryclo...@aol.com";>cherryclo...@aol.com > To:ken.ja...@emccompliance.com > CC:emc-p...@majordomo.ieee.org > > Ken, replies below. > Regards, Keith Armstrong > > In a message dated 06/01/02 06:56:46 GMT Standard Time, > ken.ja...@emccompliance.com writes: > > >> Subj:Re: EMC-related safety issues >> Date:06/01/02 06:56:46 GMT Standard Time >> From:ken.ja...@emccompliance.com (Ken Javor) >> To:cherryclo...@aol.com, cortland.richm...@alcatel.com >> CC:emc-p...@majordomo.ieee.org >> >> What an EMC engineer who understands the physics of field-to-wire coupling >> would say is that the operation of non-antenna connected electronics >> associated with one subsystem will not be degraded by close proximity with >> the non-antenna connected electronics of another subsystem. Forget 10 >> meters. Are the PCs in your office separated by 10 m? Would you expect >> two PCs stacked side-by-side or one on top of the other to interact in any
European and North American Cordage
Dear All, I remember a power cordage supplied by a manufacturer which had European and North American approvals. Does anyone know the manufacturer and type of cordage? 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. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: + 972-(0)3-5339022 Fax: + 972-(0)3-5339019 Mobile: + 972-(0)54-838175 --- 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 wrote (in ) about 'EMC-related safety issues', on Sun, 6 Jan 2002: >Quote : "Who would have expected an unterminated HCMOS gate to be >able to emit 2W at 200MHz?" > >Not me - 2 Watts of effective radiated power implies over 2.5 V/m >at 3 m! I guess I have a hard time believing that was transmitted >from an HCMOS gate. I think a little common sense will go a long >way towards retiring some of these EMC-urban legends. > >on 1/6/02 10:40 AM, cherryclo...@aol.com at cherryclo...@aol.com >wrote: > >> A.2) A portable computing device used in an automatic change machine >> on >> board transport was tested to be fully compliant with EN 55022 (approx >> = >> CISPR 22). >> I helped the manufacturer investigate complaints of interference and >> discovered that sub-fitted variant, which had not been tested for EMC >> compliance, left an HCMOS inverter IC with an unterminated inverter - >> which promptly decided to self-oscillate at 200MHz. (Many >> manufacturers >> of products with a number of build variants only test the fully-loaded >> one for EMCD compliance and assume the others are at least as good.) > >> The very interesting thing about this example is that the power-ground >> structure of the PCB made a beautifully tuned antenna and resonant >> circuit at 200MHz, so although the inverter was hard-switching and did >> not run hot, the only emissions were at the 200MHz fundamental - no >> harmonics were emitted at all. > >> Another very interesting thing is that some of the complainants had >> measured the equivalent radiated RF power from these devices as 2W. >Who would have expected an unterminated HCMOS gate to be able to emit 2W > at >200MHz? Indeed, and assuming a 5 V supply, the current would be around 400 mA. At 200 MHz, the dissipation would be several hundred milliwatts. The absence of harmonics even suggests that this gate was producing a sine-wave, which makes the figures even higher and less credible. -- 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: Comparing EMI test results
I read in !emc-pstc that Rao, Praveen wrote (in ) about 'Comparing EMI test results', on Mon, 7 Jan 2002: >I'm trying to setup a programme to compare test results (for >Radiated Emissions) between test labs. The plan is to circulate a >"Artifact" around the labs and compare the results. The test sites being >compared are Semi-anechoic Chambers v/s OATS. The source used is a >wideband "RF comb generator". I would like to understand the concept >fully before I initiate this programme. Is there any information readily >available on this topic? Any help will be greatly appreciated. Thanks. > Praveen Such tests are called 'round-robin tests', from an early form of subversive/samizdat communication - a letter bearing the signatures of several dissenters arranged in a circle so it was not possible to determine the order in which the signatures were added. A web search is likely to produce a lot of information. The main point that I remember about the protocol is that no results shall be disclosed by the testers until the circulation is complete, when all results are sent to the co-ordinators for consolidation. -- 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: Comparing EMI test results
Rao, The comb generator is not a bad choice, but a few things should be checked (yes, I've done this). First, establish the base variation in the source. No antenna, just a direct connection to the receiver/SA that you will use for the evaluation under an expected, reasonable variation in temperature and battery condition. Take enough samples over enough days to make yourself statistically comfortable with the level of uncertainty you're targeting. Second, use the volumetric calibration procedure (as required for "alternative" test facilities) on both the SAC _and_ the OATS. Having done volumetric NSAs on high quality SACs and low quality OATS, I can say there is _no_ reason the OATS can be considered a "gold standard" in all instances. Lowell Kolb of Hewlett-Packard did an excellent paper on comparison of OATS sites a few years back. I would suggest looking up his paper for an idea of OATS site to site variation. Lastly, everything I've just said will, most likely, be totally swamped by variations in the EUT setup under "real" EUT testing unless you can _strictly_ control them. Don't go there. The more "real" the simulated EUT becomes, the more variables you introduce into the site evaluation. As more variables are introduced, the greater the number of data points will be required to resolve the result. While it is obvious to the most casual observer that the simple comb generator does not represent a "real" EUT, it does represent a single frequency component at a single phase component for each of the volumetric measurement points. The best work done in this area has used a VNA for evaluation of both quantities, but from the literature, this would appear to be most useful in diagnostic applications. Empirically, if the magnitude of the seven single planar volumetric points looks good, the site is _probably_ pretty good. Of course, if the SA is systematically off at all points, check the antenna calibration! Best regards, Brent DeWitt -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Rao, Praveen Sent: Sunday, January 06, 2002 6:16 PM To: emc-p...@majordomo.ieee.org Subject: Comparing EMI test results I'm trying to setup a programme to compare test results (for Radiated Emissions) between test labs. The plan is to circulate a "Artifact" around the labs and compare the results. The test sites being compared are Semi-anechoic Chambers v/s OATS. The source used is a wideband "RF comb generator". I would like to understand the concept fully before I initiate this programme. Is there any information readily available on this topic? Any help will be greatly appreciated. Thanks. Praveen --- 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: Comparing EMI test results
Thanks for the response. The purpose is to test both, the facility (semi-anechoic v/s OATS) and the quality of results. The comb generator is my first approach. A standard test sample(with cables) will follow. Any procedures, data, results, experience on this issue ? -Original Message- From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Monday, 7 January 2002 13:47 To: Rao, Praveen; emc-p...@majordomo.ieee.org Subject: Re: Comparing EMI test results Whether a comb generator is a good artifact depends somewhat on what your purpose is. If your purpose is to check how well calibrated the site is I think a comb generator is an excellent artifact because it is physically small and should generate the same radiation pattern at all facilities. But if your purpose is to check the "quality" of the testing done at different facilities including how good the test personnel are, then I believe you need a device with attached cables, since maximizing emissions will then involve not only height searches, but also rotation of the turntable and movement of the attached cables. Maybe you can attach a cable or two to the rf jack that normally seats the stub. on 1/6/02 8:16 PM, Rao, Praveen at praveen@fujitsu.com.au wrote: > > > > I'm trying to setup a programme to compare test results (for > Radiated Emissions) between test labs. The plan is to circulate a > "Artifact" around the labs and compare the results. The test sites being > compared are Semi-anechoic Chambers v/s OATS. The source used is a > wideband "RF comb generator". I would like to understand the concept > fully before I initiate this programme. Is there any information readily > available on this topic? Any help will be greatly appreciated. Thanks. > Praveen > > > > --- > 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: Comparing EMI test results
Whether a comb generator is a good artifact depends somewhat on what your purpose is. If your purpose is to check how well calibrated the site is I think a comb generator is an excellent artifact because it is physically small and should generate the same radiation pattern at all facilities. But if your purpose is to check the "quality" of the testing done at different facilities including how good the test personnel are, then I believe you need a device with attached cables, since maximizing emissions will then involve not only height searches, but also rotation of the turntable and movement of the attached cables. Maybe you can attach a cable or two to the rf jack that normally seats the stub. on 1/6/02 8:16 PM, Rao, Praveen at praveen@fujitsu.com.au wrote: > > > > I'm trying to setup a programme to compare test results (for > Radiated Emissions) between test labs. The plan is to circulate a > "Artifact" around the labs and compare the results. The test sites being > compared are Semi-anechoic Chambers v/s OATS. The source used is a > wideband "RF comb generator". I would like to understand the concept > fully before I initiate this programme. Is there any information readily > available on this topic? Any help will be greatly appreciated. Thanks. > Praveen > > > > --- > 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
The question of ethics or morality is at the heart of this discussion which makes it much more important than technical discussions about electromagnetism, which is the ONLY reason I have pursued this so far. I was critical of the IEE safety guide on MORAL grounds. It is part of the morality which says that businessmen or producers are considered guilty until proven innocent because of what they are - profit-making producers. That it is immoral to make a profit and anyone doing so is taking advantage of someone else. This is not the morality which built the USA into the world's wealthiest nation, but it is the morality which will reduce us to the most impecunious. The strict Muslim countries that have been in the news of late forbid loaning of money at interest, because the Koran forbids usury. It is no accident that these countries all belong to the third world. Progress depends on the ability to raise capital. The most efficient way to do that is for people who have profited from past ventures to invest those profits in new ventures. That is what banks facilitate. If there are no profits, then there is no money to borrow and to start a venture and progress stops or becomes agonizingly slow. A policy which says that producers are liable for unlimited damages without needing to show defect or negligence is on a moral level with the prohibition of lending money at interest. We have to decide if we wish to live in a civilized world or not. That is a question of moral significance. The idea that businessmen are immoral greedy people who give no thought to the quality of their products is an ugly lie spread by enemies of capitalism. A little thought will show that businessmen who operate like this do not stay in business long because their products get a bad reputation. Certainly you can find examples of bad or ignorant behavior. Does this justify policies which assume all businessmen are evil and that they must be reined in by pure-hearted regulators? What makes the regulators pure-hearted? That they don't make profit, but siphon profits away? What is the cost of the regulation relative to the benefit? What marvelous inventions didn't occur because the seed money necessary to initiate a development wasn't there? When engineers make false claims that unintentional RE from ITE can cause safety-critical circuits to fail catastrophically, we engage in another moral transgression. We attempt to get a short term gain at the cost of long term loss. The short term gain is to make ourselves and our profession look more important. But the long term loss is that of the little boy who cried wolf. After a long enough period of false alarms, we will lose the respect and ear of management and if we must raise a REAL issue, it will fall on deaf ears. I have no way of knowing, but I wonder how many unfulfilled warnings the managers who OK'd the launch of 51L (Challenger) had listened to prior to making their fateful decision. on 1/6/02 10:24 AM, cherryclo...@aol.com at cherryclo...@aol.com wrote: Dear John The incubator I described was already on the EU market in the latter half of the 1990s, when I helped to test and fix it. And I'm sorry to disappoint but I have already experienced several similar examples I could quote, such as the electric blanket that would change its heat settings randomly when a bedside light was switched on or off, or from other low-level mains transients. This is a potentially fatal issue for certain kinds of invalid, or people who are blind drunk (surely no person reading this would ever be in such a state) and by the way, this is not me being emotive again, it was the expressed concern of the manufacturer and one of the reasons why they called me in. They sacked their Technical Director over this incident. They also didn't do a product recall despite having an estimated 100,000 products with the problem already out in the field. Of course, as a responsible engineer (and to cover my ass) I wrote them a letter recommending that they did a product recall (while thinking of the designers of the Challenger Space Shuttle's infamous O-ring seals). I find that many independent EMC people have dozens of similar examples, which they can't talk about very much because of commercial confidentiality.. This is one reason why the EMC + Compliance Journal (www.compliance-club.com) started its 'Banana Skins' column - to help educate practising engineers about real EMC engineering problems they almost certainly weren't taught about at college and may not (yet) have experienced for themselves. I also have personal experience of a UK company that in the late 90's was selling a range of over 110 CE-marked products (such as incubators) intended for medical and chemical laboratories although less than 10% of their products met both the EMCD and the LVD. The company in question had just been purchased by another, which is why I was involved. Interestingly, the new owners continued to s
Re: EMC-related safety issues
I do not recall a single example or argument to show what you claim. On the other hand, I have given physical and numerical arguments to back up my common sense position. on 1/6/02 10:51 AM, cherryclo...@aol.com at cherryclo...@aol.com wrote: Ken, I believe other postings on this topic this weekend clearly show that electronic circuits which were not designed as radio receivers can possibly be interfered with by the emissions from products which meet FCC/CISPR 22 limits, for a number of possible reasons, especially when the product is closer than 10 metres to the source of the emissions. Certain kinds of transducers and their amplifiers appear to be particularly at risk because of the low levels of their transducer signals. Regards, Keith Armstrong In a message dated 06/01/02 06:56:28 GMT Standard Time, ken.ja...@emccompliance.com writes: Subj:Re: EMC-related safety issues List-Post: emc-pstc@listserv.ieee.org Date:06/01/02 06:56:28 GMT Standard Time From:ken.ja...@emccompliance.com (Ken Javor) To:cherryclo...@aol.com CC:emc-p...@majordomo.ieee.org My point was that only radios are sensitive to rf fields at the levels controlled by FCC/CISPR22 and indeed, as Ing. Gremen pointed out, levels well above the limits. Which means that the only rationale behind FCC/CISPR22 is protection of radio broadcast reception. Period. on 1/5/02 12:10 PM, cherryclo...@aol.com at cherryclo...@aol.com wrote: 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 List-Post: emc-pstc@listserv.ieee.org 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.
Re: EMC-related safety issues
Quote : "Who would have expected an unterminated HCMOS gate to be able to emit 2W at 200MHz?" Not me - 2 Watts of effective radiated power implies over 2.5 V/m at 3 m! I guess I have a hard time believing that was transmitted from an HCMOS gate. I think a little common sense will go a long way towards retiring some of these EMC-urban legends. on 1/6/02 10:40 AM, cherryclo...@aol.com at cherryclo...@aol.com wrote: A.2) A portable computing device used in an automatic change machine on board transport was tested to be fully compliant with EN 55022 (approx = CISPR 22). I helped the manufacturer investigate complaints of interference and discovered that sub-fitted variant, which had not been tested for EMC compliance, left an HCMOS inverter IC with an unterminated inverter - which promptly decided to self-oscillate at 200MHz. (Many manufacturers of products with a number of build variants only test the fully-loaded one for EMCD compliance and assume the others are at least as good.) The very interesting thing about this example is that the power-ground structure of the PCB made a beautifully tuned antenna and resonant circuit at 200MHz, so although the inverter was hard-switching and did not run hot, the only emissions were at the 200MHz fundamental - no harmonics were emitted at all. Another very interesting thing is that some of the complainants had measured the equivalent radiated RF power from these devices as 2W. Who would have expected an unterminated HCMOS gate to be able to emit 2W at 200MHz?
Re: EMC-related safety issues
QUOTE: "And I don't think that 92dBuV/m is a high field strength to be emitted by a PC placed nearby, or for a non-compliant laptop at 10 metres." You may not think so, but I am sorry, the numbers just don't add up. 92 dBuV/m at 10 meters implies an effective radiated power of 5.3 mW. Consider that the source is not an intentional antenna. It will have no more directivity than a dipole and its efficiency will be much less since it isn't matched to the source. If we simply assume no gain (meaning matching losses just offset directivity) , that means 5.3 mW of rf power are emitted from the EUT or its attached cables. If one makes the reasonable assumption that it is common mode rf current which is radiating, then the potential associated with rf power will be a small number of millivolts (in the frequency domain). This in turn implies a significant fraction of an Ampere of common mode rf current. A highly unlikely situation! Once again, with an impossible conclusion, either the assumption or the logic must be wrong. You can choose to disbelieve, but please point out where the logic has gone awry. You have several times cited Mr. Woodgate for non-constructive criticism. Now I am asking you, don't give more hearsay: explain where my physics is incorrect. We are engineers here, not pollsters. And if you are saying that specification level compliance at 10 meters can scale up to 92 dBuV/m nearby, that is either false or misleading depending on the frequency range. At the low end, say 30 MHz, the area subtended by position near the offending PC isn't large enough to efficiently radiate or couple the field (the wavelength is 10 meters, and the other gentleman's antenna factor calculation assumed a tuned dipole antenna in order to get a small antenna factor). So the field will not scale up as per your prediction, and the pickup mechanism will be nowhere near the antenna factor that gentleman calculated. In fact at 30 MHz your antenna factor will be on the order of 20 dB or worse (assuming the mutual coupling length to be 1 m). At the high end (near 1 GHz) you could be in the far field in close and the field could scale up to a value of 92 dBuV/m, but the antenna factor of a matched tuned dipole at 1 GHz is 26 dB so the potential from that perfect antenna is 92 dBuV/m - 26 dB/m = 66 dBuV or 2 mV. If you consider that any signal with information content carried by 2 mV is shielded, the issue becomes, once again, a non-problem. on 1/6/02 10:43 AM, cherryclo...@aol.com at cherryclo...@aol.com wrote: Snip: And I don't think that 92dBuV/m is a high field strength to be emitted by a PC placed nearby, or for a non-compliant laptop at 10 metres.
Comparing EMI test results
I'm trying to setup a programme to compare test results (for Radiated Emissions) between test labs. The plan is to circulate a "Artifact" around the labs and compare the results. The test sites being compared are Semi-anechoic Chambers v/s OATS. The source used is a wideband "RF comb generator". I would like to understand the concept fully before I initiate this programme. Is there any information readily available on this topic? Any help will be greatly appreciated. Thanks. Praveen --- 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.
