RE: Thermocouple glue
I don't agree with the general approach and opinions on traditional yeah vs. nayjust because they ( Safety Agency) doesn't understand, if the Mfr'r uses it in the right context, and it does not promote a safety deviaition than it should be accepted... a concrete reasoning for NOT accepting it should be pushed for and confirmed by looking at the safety standard being used... one man's opinion again: Richard, From: Ralph McDiarmid [mailto:ralph.mcdiar...@xantrex.com] Sent: Monday, April 28, 2003 4:45 PM To: emc-p...@majordomo.ieee.org Subject: RE: Thermocouple glue If it can be shown that the thermocouple remains attached and in good contact with the surface to be measured, I don't know why the agencies would not accept the use of thermal grease. There concern might be the affect the thermal compound has on the adhesive of the tape. Sometimes, they oppose things they simply don't understand or have no experience with. Fair enough, I suppose, I can see their point of view and they must take a conservative approach at all times. Ralph McDiarmid, AScT Compliance Engineering Group Xantrex Technology Inc. www.xantrex.com From: Brian O'Connell [mailto:boconn...@t-yuden.com] Sent: April 28, 2003 9:55 AM To: emc-p...@majordomo.ieee.org Subject: RE: Thermocouple glue My use of thermal grease was discontinued several years ago by request of various agency engineers reviewing test data/technique. And more recently, during my ISO 17025 audit, the NCB auditor explicitly directed me to never use thermal grease for thermocouple application. And auditors from other NRTLs/NCBs have emphasized, at least verbally, that thermal grease is not acceptable. R/S, Brian -Original Message- From: Ron Pickard [ mailto:rpick...@hypercom.com] Sent: Friday, April 25, 2003 10:19 AM To: emc-p...@majordomo.ieee.org Subject: Re: Thermocouple glue To all, I'm surprised that no one hasn't mentioned this yet. In the past for this application, the securement that I was introduced to was fiberglass tape and that white thermal grease. The tape exhibited high thermal stability and was used to secure the thermocouples, but left adhesive residue when removed after a temperature test. The thermocouple was inserted into the grease which offered excellent thermal conduction from the measurement point to the thermocouple. The downside to this grease, as anyone who's used this grease would say, is that the grease is messy to the extreme and it generally could not be completely removed from any surface that it came in contact with. And, it always found a way to get onto unintended surfaces including clothing. But, as a plus, the thermal grease would stay put physically over a very wide temperature range.
RE: OK, what's going on?
Mark mentioned reports, a paper trail...or is it? Vendors doing the EMC/EMI ?, who might a vendor be for say IBM or Dell? would think the mfr'r would have an associate there during testing like most of us do. Seems it would be easy to look at the report, from which test lab did it, are they accredited? if yes, then there shouldnt be any questions.. only thing I see, maybe Disparity, as readings can be differnet from lab to lab. these days its ship now...or not at all.. and barely passing for PC's, since its class B may be enough for the PC companies. Richard, From: Mark Kirincic [mailto:mkirin...@houston.rr.com] Sent: Thursday, March 27, 2003 8:55 AM To: lfresea...@aol.com; emc-p...@majordomo.ieee.org Subject: Re: OK, what's going on? I guess now its my turn to put in my two cents. The major reason that you are having a hard time finding units that pass is that all these major computer companies rely on their vendors to test the products to FCC and CE limits. Since the majority of these companies have suppliers in the Taiwan and China all of these units pass due to pressure from the major computer companies and the vendors themselves. These major computer companies then try to legitimize it by getting copies of test reports showing the units are in compliance. None of these companies will report each other to the authorities mainly because they can not guarantee that all of their products pass and they fear retaliation. Their philosophy is as long as we have this report we can sell this product until someone catches us and then they go into a major scramble to fix the problem that was uncovered. The only way to reduce this is through FCC and CE random audits. I have worked for several major computer companies in my 19 years of experience, and they all share this philosophy. One former company was the exception, they were deathly afraid of bad press and they went to great extremes to make sure their products passed with adequate margin. I will get off my soap box now. Mark J. Kirincic mkirin...@houston.rr.com - Original Message - From: lfresea...@aol.com To: emc-p...@majordomo.ieee.org Sent: Tuesday, March 25, 2003 2:05 PM Subject: OK, what's going on? Hi all, This e-mail has been prompted because of a number of things that have all come together. This may take a little reading, but please stick with it. Last note... this is not intended to pick on any individuals, or organization, but I do want to stir the pot. I operate an engineering lab, helping clients harden their designs to meet EMC requirements. In this particular instance, I was working for a small client, on a card that goes in the PC . In order to test I need a host PC. So, to save money, the card maker supplies 2 clones. Neither of the two PCs passed emissions testing with the card, in fact, above 100 MHz, they fail even the Class A limit: badly! So, before calling my client, I pull his card, the PC is no different, I pull the monitor, then the keyboard, then the mouse... No different. I test just the PC chassis one at a time. On their own, booted and then the peripherals removed. Not even close to passing. Disgruntled, I get my office PC... Fail. I get my kids PC.. over 20 dB over the limit! So, I think so much for clones... I buy 2 Dell ( sorry, no point trying to hide names... ) desktops, both fail, quite badly. However, they have very similar noise profiles... Can 5 PC's all fail? I think my measuring system is set -up wrong. So I verify this. I am within 1 dB of what I expect when I inject a signal from a signal generator and account for antenna factors. Here lies the question: why can I not find a PC that passes? Worse, since they don't pass, who is chasing them down to enforce the requirements? I'm unhappy, because I am taking a clients money to make him meet the requirements, when it seems no one else is. Now, what's making this worse for me, is that I am an EMC Lab assessor. So, I go to labs and make them jump through hoops so that they produce, as consistently as possible, data the characterizes a product. Exercises, like those performed by USCEL, show that labs can have very consistent results. Anyone that stands up and says EMC is not a field where consistency can be achieved, should not be in the compliance business: please close your lab. So if the test are consistent, why the HUGE variations? In the 20+ labs I have assessed, I feel that almost every one had an ethical approach. Ironically, I felt that the bigger companies I visited like HP and Intel were exceptional: both ethically and technically. The rest of the labs were between good to very good. So cheating is unlikely.. I have now spent about 60 man-hours looking for a PC that passes FCC Class B emissions. Something that I should just be able to go to the store and get. As yet, I have no PC. Our field, it appears, is not a level playing field. It appears more like a rugby game in which we have no referee! So why are
RE: OK, what's going on?
There has been an enormous amount of feedback from Dereks email this week. Including mine. I am beginning to get the notion this is all brand new to most of the people here.. it isn't..going on for years... were not going to change evolution, we can gripe and complain best thing to do is our own diligence on our product,..not censor someone elses... what do you do to the company that passes site A oats,then fails site B...go to site C?...best 2 out of 3? think bill gates would care if he sold PC's? and not just software...People who rely on word/excel and other programs would care less about failing by a few db. the FCC is in place they run itwe try our best Richard, From: drcuthbert [mailto:drcuthb...@micron.com] Sent: Friday, March 28, 2003 10:54 AM To: 'Mark Kirincic'; Stone, Richard A (Richard); lfresea...@aol.com; emc-p...@majordomo.ieee.org Subject: RE: OK, what's going on? What would NARTE say about certified EMC engineers and technicians signing off on equipment that does not make the grade? It would be great if everyone and every company handled the issue of EMC ethically. But since the world does not always work this way...I favor the idea of a fine for every unit that is shipped from a lot that statistically fails. I.E. mandatory sampling (of boxed and shipped units) and only a certain percentage are allowed to fail, etc. Companies would then weigh the cost of compliance against the cost of non-compliance. Devils advocate speaking now: But from the viewpoint of economics this would of course add cost to every unit shipped. Is the additional manufacturing cost to the public offset by any savings due to lower emissions and lower susceptibility? Would society truly benefit from better EMC enforcement or does this serve only the EMC community? Dave Cuthbert Micron Technology From: Mark Kirincic [mailto:mkirin...@houston.rr.com] Sent: Thursday, March 27, 2003 8:53 PM To: Stone, Richard A (Richard); lfresea...@aol.com; emc-p...@majordomo.ieee.org Subject: Re: OK, what's going on? To further clarify my point, all the major companies are guilty of this. I know of first hand information where a unit passed in Asia and failed here in the states at the companies test lab, and they are forced by upper management to ship the product anyway. These companies are trying to get their product out the door as cheaply as possible with little to no concern about the consequences. I have read in some of the responses that we should fine these companies, that is a good point but that is only a slap on the wrist and a chance most of them are willing to take. In my opinion, what really needs to be done is full accountability for failed products that the company by having the company name made public at the FCC and CE websites and trade journals. Also have the companies pay for audits of all the units that are in the country that fail to meet FCC and CE standards. What I am saying is to charge a flat fee per unit that fails. Secondly, I would prevent them form selling into a market segment if the audit shows non compliance of multiple units. Have the company provide future proof of compliance before shipping which will hurt them in their pocket book a lot more than just a simple fine. Mark J. Kirincic mkirin...@houston.rr.com - Original Message - From: Stone, Richard mailto:rsto...@lucent.com A (Richard) To: 'Mark Kirincic' mailto:mkirin...@houston.rr.com ; lfresea...@aol.com ; emc-p...@majordomo.ieee.org Sent: Thursday, March 27, 2003 8:34 AM Subject: RE: OK, what's going on? Mark mentioned reports, a paper trail...or is it? Vendors doing the EMC/EMI ?, who might a vendor be for say IBM or Dell? would think the mfr'r would have an associate there during testing like most of us do. Seems it would be easy to look at the report, from which test lab did it, are they accredited? if yes, then there shouldnt be any questions.. only thing I see, maybe Disparity, as readings can be differnet from lab to lab. these days its ship now...or not at all.. and barely passing for PC's, since its class B may be enough for the PC companies. Richard, From: Mark Kirincic [mailto:mkirin...@houston.rr.com] Sent: Thursday, March 27, 2003 8:55 AM To: lfresea...@aol.com; emc-p...@majordomo.ieee.org Subject: Re: OK, what's going on? I guess now its my turn to put in my two cents. The major reason that you are having a hard time finding units that pass is that all these major computer companies rely on their vendors to test the products to FCC and CE limits. Since the majority of these companies have suppliers in the Taiwan and China all of these units pass due to pressure from the major computer companies and the vendors themselves. These major computer companies then try to legitimize it by getting copies of test reports showing the units are in compliance. None of these companies will report each other to the authorities mainly
RE: OK, what's going on?
out of the box passed, thats important, built and shipped correctly... once you transport,' was it packaged the EXACT same way Geoerge, as you moved it to site # 2 for the second EMI test. odds are not...I have been guilty of moving equipment and seeing a change in emi profile.. alwyas for the worse...never better, Richard From: George Stults [mailto:george.stu...@watchguard.com] Sent: Thursday, March 27, 2003 9:39 PM To: Cortland Richmond; lfresea...@aol.com; ieee pstc list Subject: RE: OK, what's going on? I suppose that vibration may be good to a point, but I offer the following. I bought a pair of PC's (These were Dell Dimension 500 and they did pass Class B) out of the box. I found however that after many repeated trips to the lab in my car, they no longer did. The I/O connectors did degrade somewhat, but the noise leakage was traced to the case. It appeared that the problem was fretting due to vibrating metal to metal contacts along various seams in concert with some kind of coating on the surfaces. Where metal fingers met metal surface, a kind of black marking had developed and I found it couldn't be cleaned with alcohol etc. Light sandpapering didn't help much either, although I suppose a dremel tool might have worked. Copper tape along the affected seams did work, but of course then, I had modified it George Stults WatchGuard Technologies Inc. From: Cortland Richmond [mailto:72146@compuserve.com] Sent: Thursday, March 27, 2003 11:10 AM To: lfresea...@aol.com; ieee pstc list Subject: Re: OK, what's going on? Derek wrote: the EUT should have been exposed to simulated shipping and installation by a user... FWIW, in the 1980's I worked in an audit lab where we tested samples of shipped equipment for FCC, vibration, heat, humidity, temperature, TEMPEST... it was not uncommon for equipment to do BETTER in EMC tests after it had been subjected to vibration testing. With oils, oxides and so on having been abraded, metal parts made better contact with each other. Cortland This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: OK, what's going on?
Derek, doesnt say whether you took the uncompliant equipment straight from your lab to another without making any changes... be interesting to see what the data is, since PC's are listed to class B... you may have something.. but its always good to get a second result from lab B. Richard, From: lfresea...@aol.com [mailto:lfresea...@aol.com] Sent: Tuesday, March 25, 2003 3:05 PM To: emc-p...@majordomo.ieee.org Subject: OK, what's going on? Hi all, This e-mail has been prompted because of a number of things that have all come together. This may take a little reading, but please stick with it. Last note... this is not intended to pick on any individuals, or organization, but I do want to stir the pot. I operate an engineering lab, helping clients harden their designs to meet EMC requirements. In this particular instance, I was working for a small client, on a card that goes in the PC . In order to test I need a host PC. So, to save money, the card maker supplies 2 clones. Neither of the two PCs passed emissions testing with the card, in fact, above 100 MHz, they fail even the Class A limit: badly! So, before calling my client, I pull his card, the PC is no different, I pull the monitor, then the keyboard, then the mouse... No different. I test just the PC chassis one at a time. On their own, booted and then the peripherals removed. Not even close to passing. Disgruntled, I get my office PC... Fail. I get my kids PC.. over 20 dB over the limit! So, I think so much for clones... I buy 2 Dell ( sorry, no point trying to hide names... ) desktops, both fail, quite badly. However, they have very similar noise profiles... Can 5 PC's all fail? I think my measuring system is set -up wrong. So I verify this. I am within 1 dB of what I expect when I inject a signal from a signal generator and account for antenna factors. Here lies the question: why can I not find a PC that passes? Worse, since they don't pass, who is chasing them down to enforce the requirements? I'm unhappy, because I am taking a clients money to make him meet the requirements, when it seems no one else is. Now, what's making this worse for me, is that I am an EMC Lab assessor. So, I go to labs and make them jump through hoops so that they produce, as consistently as possible, data the characterizes a product. Exercises, like those performed by USCEL, show that labs can have very consistent results. Anyone that stands up and says EMC is not a field where consistency can be achieved, should not be in the compliance business: please close your lab. So if the test are consistent, why the HUGE variations? In the 20+ labs I have assessed, I feel that almost every one had an ethical approach. Ironically, I felt that the bigger companies I visited like HP and Intel were exceptional: both ethically and technically. The rest of the labs were between good to very good. So cheating is unlikely.. I have now spent about 60 man-hours looking for a PC that passes FCC Class B emissions. Something that I should just be able to go to the store and get. As yet, I have no PC. Our field, it appears, is not a level playing field. It appears more like a rugby game in which we have no referee! So why are there no fines being levied? Especially since it seems I can find non-compliant products everywhere! Is the self policing approach out of control? I intend to take this up with the FCC. Is there anyone out there that is supportive of this action ( which means you must be doing things right.. )? Am I wasting my time ( in which case if this is all lip service... why should we even test )? Or am I missing something ( I listen to 2 by 4's )? Derek Walton Owner of an EMC Lab EMC Lab Assessor NARTE EMC Engineer 30 years of EMC experience
RE: OK, what's going on?
thats true Earl, good point on company B, not caring but selling with a higher profit, less EMC..company A busting butt to pass and comply with integrity. as for immunity... do any PC makers manufacturer any PC's strictly for sales in USA...only need Emissions here. that would save 1000's in emc costs, never mind engineering to fix the problems.. of course you would need diff. p/n's then. and sales,manuals, compliance certs..etc would be altered. has anyone ever done a cost estimate based on building a USA vs. EU chassis? curious to see if its worth the time. From: Morse, Earl (E.A.) [mailto:emo...@ford.com] Sent: Wednesday, March 26, 2003 11:10 AM To: 'Grasso, Charles'; 'lfresea...@aol.com'; emc-p...@majordomo.ieee.org Subject: RE: OK, what's going on? Amen! I had 15 years of computer EMC when I left the PC sector this year. This was a never ending source of frustration. I won't even get into the shortcomings of the measurement standards. The emigration of PC manufacturing to the PAC rim is being followed by emigration of the design and validation teams also. Many PC manufacturers have completely outsourced their EMC testing to the OEM PC manufacturers even when they own several 10 meter semi anechoic chambers. This is akin to having the fox watch over the hen house. Management says it is more economical that way. When every test is compliant and product passes the first time every time then I guess it is. Besides, it isn't compliance that anyone is really after anymore but rather a piece of paper that says it is compliant. (Neville Chamberlain effect) Maybe it doesn't matter anyway. Most customers don't care if it meets EMC requirements. Most only relate features to price and EMC is not a feature they would pay for. An EMC engineer can't tell whether a PC passes or fails without an expensive test site chock full of equipment so how is a consumer supposed to tell? A few commercial and government customers perform audit tests before entering into contracts but most don't seem to care. I seem to remember an FCC employee speaking at a conference somewhere stating that they don't get computer interference complaints. Mostly telephone interference complaints but never computer interference. Most of the field complaints I worked on were immunity related. Customers care and complain about that. In today's computer industry the companies that aggressively pursue EMC are penalized by adding more cost while the companies that ignore it are able to produce a more inexpensive product. The vigilant companies will not be able to compete. I agree, enforce the emissions standards or drop them. Earl Morse ex-Major PC Company EMC guru -Original Message- From: Grasso, Charles [mailto:charles.gra...@echostar.com] Sent: Tuesday, March 25, 2003 7:38 PM To: 'lfresea...@aol.com'; emc-p...@majordomo.ieee.org Subject: RE: OK, what's going on? Hi Derek - Go Reds!! This is not a surprise to me. I have railed at much length a couple of years ago as to the latest FCC changes to the emissions qualification. I am sure you are familiar with it so I won't belabour the point. Fundementally the FCC PC emissions procedure has rendered the EMC discipline almost irrelevent. The new procedures coupled with the lack of enfocement makes it difficult to justify the increased costs of EMC design test. It also makes the whole measurement uncertainty push ridiculous. After all if the procedures allow for prodcut that 20dB out of spec why bother with a couple of dB of error?? Lets give the emissions standards some teeth or eliminate it all together. Best Regards Charles Grasso Senior Compliance Engineer Echostar Communications Corp. Tel: 303-706-5467 Fax: 303-799-6222 Cell: 303-204-2974 Email: charles.gra...@echostar.com; mailto:charles.gra...@echostar.com; Email Alternate: chasgra...@ieee.org From: lfresea...@aol.com [mailto:lfresea...@aol.com] Sent: Tuesday, March 25, 2003 1:05 PM To: emc-p...@majordomo.ieee.org Subject: OK, what's going on? Hi all, This e-mail has been prompted because of a number of things that have all come together. This may take a little reading, but please stick with it. Last note... this is not intended to pick on any individuals, or organization, but I do want to stir the pot. I operate an engineering lab, helping clients harden their designs to meet EMC requirements. In this particular instance, I was working for a small client, on a card that goes in the PC . In order to test I need a host PC. So, to save money, the card maker supplies 2 clones. Neither of the two PCs passed emissions testing with the card, in fact, above 100 MHz, they fail even the Class A limit: badly! So, before calling my client, I pull his card, the PC is no different, I pull the monitor, then the keyboard, then the mouse... No different. I test just the PC chassis one at a time. On their own, booted and then the peripherals removed. Not even close
RE: Fw, Yahoo Groups Recommendation?: Changes to IEEE emc-pstc we b-based services...
Brian, the firewalls exist for many of us, concerning emailing and free accounts, your right,its with corporate, not Yahoo.. From: Brian Epstein [mailto:brian.epst...@veeco.com] Sent: Thursday, March 13, 2003 2:59 PM To: 'Garnier, David S (MED)'; 'Guy Boone'; emc-p...@majordomo.ieee.org Subject: RE: Fw, Yahoo Groups Recommendation?: Changes to IEEE emc-pstc we b-based services... The problem isn't with Yahoo. You need to spank your net nanny. From: Garnier, David S (MED) [mailto:david.garn...@med.ge.com] Sent: Thursday, March 13, 2003 9:54 AM To: 'Guy Boone'; emc-p...@majordomo.ieee.org Subject: RE: Fw, Yahoo Groups Recommendation?: Changes to IEEE emc-pstc we b-based services... Pardon me if this has been decided already but I think you need to be made aware of this. Our corporate net nanny has blocked access to all Yahoo accounts (and other free mail accounts) - moving the EMC listserve there would prevent access from anyone within the GE.COM domain. Our local IEEE EMC chapter is blocked, (all appeals for access have been ignored.) You might me asking yourself why should I care? (Dave could certainly subscribe to the listserve at home - ((please enable the digest mode.)) This company is a trendsetter and many others emulate our practices, your impending move may impact other subscribers in the future. David Garnier e GE Medical Systems ___ David S. Garnier Senior Technician PET Engineering 3000 N. Grandview Ave - M/S W-1250 Waukesha, Wi. 53188 Tel: 262.312.7246 From: Guy Boone [mailto:bo...@sympatico.ca] Sent: Wednesday, March 05, 2003 3:24 PM To: emc-p...@majordomo.ieee.org Subject: Fw, Yahoo Groups Recommendation?: Changes to IEEE emc-pstc web-based services... Jim/Richard; Any update on the data transfer from http://ieeepstc.mindcruiser.com/ http://ieeepstc.mindcruiser.com/ to ttps://www.ieeecommunities.org/emc-pstc https://www.ieeecommunities.org/emc-pstc... or a tentative date? For your information... the Yahoo group http://groups.yahoo.com/group/emc-pstc/ http://groups.yahoo.com/group/emc-pstc/ can be easily configured to operate both as a listserver-based service and a web-based service. As a web-based service, https://www.ieeecommunities.org/emc-pstc https://www.ieeecommunities.org/emc-pstc does offer some advantages over Yahoo Groups (as referenced below)... but as a listserver-based service, it's advantage over majordomo is that it allows the member to control the delivery of messages (ie, individual emails, daily digest or no email) and messages can be viewed online http://groups.yahoo.com/group/emc-pstc/messages. I would recommend that you consider a migration to Yahoo Groups, once the data transfer to https://www.ieeecommunities.org/emc-pstc https://www.ieeecommunities.org/emc-pstc is complete. Should the planned data transfer be not possible, you may want to consider a full migration to Yahoo Groups, as listserver/web-based solution. Here in Ottawa, Canada... we have a group called RAFT - Regulatory Approvals Forum for Technology, and have been using Yahoo Groups http://groups.yahoo.com/group/RAFT-Global/ http://groups.yahoo.com/group/RAFT-Global/ for the past 2 years. I have joined http://groups.yahoo.com/group/emc-pstc/ http://groups.yahoo.com/group/emc-pstc/ some time ago... If you want to give it some consideration, I can volunteer to make the additional configuration changes. Please let me know your thought, and the Group owner will need to have me assigned as Moderator. Regards, http://ca.geocities.com/guyboone/My_Page.html Guy Boone, P. Eng Electrical Engineer, specializing in Safety Compliance, Power/Control Systems Design Buildings Engineering Steering Committee Member - http://www.raft-global.org/ www.RAFT-Global.org 35 Athena Way Tel: 613-823-7534 Ottawa (Nepean), ON K2G 6S1 Cell: 613-850-6533 From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Jim Bacher Sent: January 23, 2003 10:54 AM To: 'Andre, Pierre-Marie'; emc-p...@majordomo.ieee.org Subject: RE: EMC-PSTC Email Forum We have had a couple major glitches with the movement of data. We are working on an alternate solution to the issue. As soon as we have worked out the details we will let you know. Jim From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Andre, Pierre-Marie Sent: January 23, 2003 4:24 AM To: emc-p...@majordomo.ieee.org Subject: EMC-PSTC Email Forum On the http://www.ewh.ieee.org/soc/emcs/pstc/index.html http://www.ewh.ieee.org/soc/emcs/pstc/index.html I can read : The EMC-PSTC archives will be moved to another site shortly. The new location will be announced shortly. Make sure you check here often. Is there any target date to make the new location available? Many thanks for
RE: Ethernet coax connection
we've had good success with the built capacitance of 9000pf as well, depending on test being discussed and frequency, certain cap. values from the shielded ring of the UNgrounded ring to earth works well for low freq.. 30 mhz. Richard, From: Knighten, Jim L [mailto:jk100...@teradata-ncr.com] Sent: Wednesday, March 05, 2003 4:12 PM To: Ken Javor; emc-p...@majordomo.ieee.org Subject: RE: Ethernet coax connection Ken, It is a potential shock hazard if the coax run is long and runs from building to building (for instance) where the ground potentials may be different in the different buildings. One can develop a large potential on the shield of the cable, so that if you put yourself between the cable shield and ground you may get a strong shock. That is the reason for isolating the shield from more than one direct connection to ground. It is a real issue. The result for EMI is, as you have noted, the creation of an egregious EMI offender. I have used the chassis mounted BNC connectors with built-in capacitors successfully. Jim Jim Knighten, Ph.D. Teradata, a Division of NCR http://www.ncr.com 17095 Via Del Campo San Diego, CA 92127 USA Tel: 858-485-2537 Fax: 858-485-3788 jim.knigh...@ncr.com -Original Message- From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Wednesday, March 05, 2003 12:58 PM To: Knighten, Jim L; emc-p...@majordomo.ieee.org Subject:Re: Ethernet coax connection Assume complete ignorance on my part. What is the safety concern? on 3/5/03 3:50 PM, Knighten, Jim L at jk100...@teradata-ncr.com wrote: Ken, Safety considerations are the reason for the spec requirement. You are allowed to ground the shield at one point. Try using a BNC coax connector with a built-in capacitor to ground. That gives you an AC connection to ground and is often quite effective. These are off-the-shelf parts. Jim Jim Knighten, Ph.D. Teradata, a Division of NCR http://www.ncr.com 17095 Via Del Campo San Diego, CA 92127 USA Tel: 858-485-2537 Fax: 858-485-3788 jim.knigh...@ncr.com -Original Message- From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Wednesday, March 05, 2003 12:38 PM To: emc-p...@majordomo.ieee.org Subject: Ethernet coax connection Question for list members: Background: I am troubleshooting a complex integration of military hardware and COTS. One COTS piece of equipment has an RG-58 coaxial connection, but the coax connector is an isolated feedthrough bnc. From a radiated emissions point-of-view, that is hurting us. One of the engineers here said that is part of the spec - Ethernet shields are not supposed to be chassis grounded. Question: Can someone please explain the reason for that, and how this is usually handled to minimize radiated emissions? Thank you. Ken Javor EMC Compliance Huntsville, Alabama 256/650-5261 --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc -- Ken Javor EMC Compliance Huntsville, Alabama 256/650-5261 This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute:
RE: EMC-Related Functional Safety
what the heck does that mean? was he of the wrong nationality too? maybe crippled? From: Daniel Forrest [mailto:daniel.forr...@at.flextronics.com] Sent: Thursday, February 13, 2003 1:21 AM To: 'Richard Hughes'; 'Stone, Richard A (Richard)'; 'Brent DeWitt'; emc-p...@majordomo.ieee.org Subject: RE: EMC-Related Functional Safety I can only presume that both the EMC Directive and the LVD will never account for the fact that the guy was American. From: Richard Hughes [mailto:rehug...@nortelnetworks.com] Sent: Wednesday, February 12, 2003 4:35 PM To: 'Stone, Richard A (Richard)'; 'Brent DeWitt'; emc-p...@majordomo.ieee.org Subject: RE: EMC-Related Functional Safety Richard, I think that you may be getting things mixed up. The aspect of Functional Safety that was being discussed is when a safety hazard results from the equipment under consideration being exposed to a level of em radiation greater than that which it was designed for. We are not discussing whether it is possible to increase emissions due to a single fault. In fact this topic has been discussed in the LVD Working Party with a particular situation as follows. The issue was caused by an electronically controlled bread-toaster. The consumer had put his newspaper on the (cold) toaster - presumably due to lack of space in his kitchen. He then received an incoming call on his mobile 'phone, which turned his toaster on (due to lack of immunity). The hot toaster then set the newspaper on fire. Personally, I am not convinced that simply carrying out single fault testing will ensure that there is no safety hazards in all cases. It really depends on the design of the electronics in the equipment. Perhaps the design requires two separate transistors to be turned on by two independent microprocessors in order to create some kind of hazard. However, if the immunity of the system is poor then both of these microprocessors could generate signals that turn both of these transistors ON. Of course, this is just a thought experiment and I have no personal experience of this being a problem in real life. With safety it is very difficult to prove that a hazard can not exist by inspection of the design when - as Ken Javor said - Genius has its limits, but ignorance has none. While I am on line, I never said that the content of the article was technically good, only that it was interesting! It has certainly caused a stir. Regards, another Richard. From: Stone, Richard A (Richard) [mailto:rsto...@lucent.com] Sent: 12 February 2003 13:23 To: 'Brent DeWitt'; emc-p...@majordomo.ieee.org Subject: RE: EMC-Related Functional Safety its not the fault of a component that concerns me For EMI interference,just running normal., a very loud radiator could interfere with something else, wheel chair controller, as mentioned, thats why testing is critical...now for the fault! Not an expert, but a component fault,typically may make something not work, but worse emissions as a result? anyone have information on this event? thanks, Richard, From: Brent DeWitt [mailto:bdew...@ix.netcom.com] Sent: Tuesday, February 11, 2003 9:39 PM To: emc-p...@majordomo.ieee.org Subject: RE: EMC-Related Functional Safety Gregg, As an EMC engineer and a member of the IEC committee that wrote the 2nd edition of IEC 60601-1-2, I find your challenge interesting. First, I have to say I was not impressed with the referenced article. Facts were played a little bit too loose for my preferences. That said, I strongly believe that EMI is an inseparable portion of product safety. You mention that EMC interferes and I agree. When it interferes with a wheelchair controller and drives the patient into traffic or causes an infusion pump to triple the drug delivery rate, it can kill. I don't believe I have enough product safety experience to say if those same failures could have been caused by single component faults, but I suspect that a real world examination of the product has a significant possibility of missing the single component that was effected. I can say from 15 years or so experience that it takes much less than a microwave oven to cause medically critical control electronics to misbehave. Regards, Brent DeWitt Datex-Ohmeda Louisville, CO From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Gregg Kervill Sent: Tuesday, February 11, 2003 12:14 PM To: 'Richard Hughes'; 'drcuthbert'; emc-p...@majordomo.ieee.org Subject: RE: EMC-Related Functional Safety I fully agree with Richard Hughes - it is an interesting article but those of us who have conducted Flight Safety work will find it VERY weak is its content and treatment. Whilst EMC interferes (unless you are sitting in a microwave oven) - it is Product Safety (or the lack thereof) that kills! Furthermore I challenge anyone to demonstrate that the EMC related fatalities could not have been caused by a single components failure. Best regards
RE: EMC-Related Functional Safety
its not the fault of a component that concerns me For EMI interference,just running normal., a very loud radiator could interfere with something else, wheel chair controller, as mentioned, thats why testing is critical...now for the fault! Not an expert, but a component fault,typically may make something not work, but worse emissions as a result? anyone have information on this event? thanks, Richard, From: Brent DeWitt [mailto:bdew...@ix.netcom.com] Sent: Tuesday, February 11, 2003 9:39 PM To: emc-p...@majordomo.ieee.org Subject: RE: EMC-Related Functional Safety Gregg, As an EMC engineer and a member of the IEC committee that wrote the 2nd edition of IEC 60601-1-2, I find your challenge interesting. First, I have to say I was not impressed with the referenced article. Facts were played a little bit too loose for my preferences. That said, I strongly believe that EMI is an inseparable portion of product safety. You mention that EMC interferes and I agree. When it interferes with a wheelchair controller and drives the patient into traffic or causes an infusion pump to triple the drug delivery rate, it can kill. I don't believe I have enough product safety experience to say if those same failures could have been caused by single component faults, but I suspect that a real world examination of the product has a significant possibility of missing the single component that was effected. I can say from 15 years or so experience that it takes much less than a microwave oven to cause medically critical control electronics to misbehave. Regards, Brent DeWitt Datex-Ohmeda Louisville, CO From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Gregg Kervill Sent: Tuesday, February 11, 2003 12:14 PM To: 'Richard Hughes'; 'drcuthbert'; emc-p...@majordomo.ieee.org Subject: RE: EMC-Related Functional Safety I fully agree with Richard Hughes - it is an interesting article but those of us who have conducted Flight Safety work will find it VERY weak is its content and treatment. Whilst EMC interferes (unless you are sitting in a microwave oven) - it is Product Safety (or the lack thereof) that kills! Furthermore I challenge anyone to demonstrate that the EMC related fatalities could not have been caused by a single components failure. Best regards Gregg From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Richard Hughes Sent: Tuesday, February 11, 2003 11:01 AM To: 'drcuthbert'; emc-p...@majordomo.ieee.org Subject: RE: EMC-Related Functional Safety Dave, As you say, an interesting article. Note however that it states in regard to the LVD that: The Low Voltage Directive (LVD) Although the LVD (73/23/EEC, modified by 93/68/EEC) is generally reckoned to cover functional safety, there are no words in its text that specifically mention it - never mind EMC-related functional safety While this is accurate as far as it goes (and remembering that the Safety Objectives of the LVD were published in 1973), it could give people a false impression. The February 2001 version of the Commission publication GUIDELINES ON THE APPLICATION OF COUNCIL DIRECTIVE 73/23/EEC states: The Commission interpret that all electromagnetic aspects relating to safety including functional safety are covered by the LVD. Many of you will be aware that a revision to the LVD is underway. At the present state of discussions the draft essential requirements are far more detailed than the old safety objectives and certainly include this issue. Of course, what the final text will be is not known with certainty at this time. Regards, Richard Hughes Personal opinions only, of course. -Original Message- From: drcuthbert [ mailto:drcuthb...@micron.com] Sent: 10 February 2003 19:27 To: emc-p...@majordomo.ieee.org Subject: EMC-Related Functional Safety
RE: Earthing through screws.
adding to a long screw with additional nuts and wires is OK, as long as the first lug/wire is tied to chassis with its dedicated nut, then more can be added, as long as the first is not disturbed.. Richard, -Original Message- From: Gary McInturff [mailto:gary.mcintu...@worldwidepackets.com] Sent: Tuesday, September 17, 2002 11:02 AM To: Chris Maxwell; David Sproul; Doug McKean Cc: EMC-PSTC Subject: RE: Earthing through screws. The primary screw has the ground symbol (upside down Christmas tree) in a circle, all other locations you want to indicate as ground, called PROTECTIVE BONDING SCREWS by the standard can use the symbol but without the circle, but it is not required to mark them. At least that's the word from UL 60950 section 1.7.7.1. Heck the screws that bond the cover to the base and its connection to the primary earthing connector are examples of this type of bonding. If you had two separate chassis with signal and other non-primary power interconnects, you might pass bonding through a braid strap or something as well. Reaching here, because I can't think of a time I didn't cram everything into a single enclosure. Gary -Original Message- From: Chris Maxwell [mailto:chris.maxw...@nettest.com] Sent: Tuesday, September 17, 2002 4:08 AM To: David Sproul; Doug McKean Cc: EMC-PSTC Subject: RE: Earthing through screws. David, Your question isn't so stupid as you say. It is correct that the primary grounding screw (the first screw connected to the ground wire from the AC inlet) shouldn't be used for any purpose other than grounding. However, the standards do allow that screws and fasteners can be used to pass this grounding on to other parts of the chassis. In that context (I guess you could call them secondary ground screws), your question is valid. It is worthwhile considering labeling these screws with a ground label; especially if a user could remove this screw and still operate the product. I guess what I'm trying to say is: your specific question may have an obvious answer; but the fact that you were thinking about how to make the product safe is just as important as quoting any standard chapter and verse. It is never stupid to use logic and reason along with the standards. 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 | A friend is a person who knows the song in your heart because they stopped singing their own song long enough to hear yours :-) -Original Message- From: David Sproul [SMTP:david.spr...@alexanderlynn.co.uk] Sent: Monday, September 16, 2002 5:46 PM To: Doug McKean Cc: EMC-PSTC Subject: RE: Earthing through screws. Hello Doug, I believe you are right. If I had taken the trouble to read EN60950 para 2.6.5.7, I would have saved my self from asking stupid questions. Thanks also to all those who responded to my orignial posting. regards, David Sproul. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list
RE: Isolated grounds in central office
thanks Joe, many of us share your opinions... will await more on this subject. Richard -Original Message- From: j...@aol.com [mailto:j...@aol.com] Sent: Tuesday, September 10, 2002 2:58 PM To: emc-p...@majordomo.ieee.org Cc: jfinlay...@telica.com; dorin.op...@alcatel.com; john.juh...@ge-interlogix.com Subject: Isolated grounds in central office In a message dated 9/10/2002John Juhasz writes: Be careful Dorin. For Central Offices, they need to be isolated. Hi Guys: I changed the subject heading on this response (was Inrush and EN61000-3-3) to better reflect the direction this thread has taken. The subject of isolating circuit ground from frame ground in a CO seems to be controversial. On one hand, I have heard stories such as John's about various RBOCs insisting on this. On the other hand, I have not seen the actual written requirements that were being imposed or the rationale behind them. For safety, functionality, and EMC considerations, I think it is generally better to tie circuit ground to frame ground in a robust fashion. One person told me that Verizon had insisted that circuit ground be brought out to an isolated terminal post that could then be externally tied to frame ground. This made a mess out of his design, and so far I have avoided this approach in my own designs without getting nailed. It seems that there is some confusion about whether this isolation is required and if so, why it is required. The whole subject of grounding within a CO can become quite complicated, especially when lightning is taken into consideration. I understand that TR-NWT-000295, Isolated Ground Planes: Definition and Application to Telephone Central Offices addresses some of these issues, but not in a clear manner (imagine that for a Telcordia document!). If anyone can provide a clear explanation of when isolation of circuit ground and frame ground is required in a C.O. and why, I would be most interested to know. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com
RE: Telephone headsets
does anyone know about: RRL a standard/requirement in south korea? what equipment must comply to it? thank you, Richard, -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: Friday, August 30, 2002 12:14 PM To: emc-p...@majordomo.ieee.org Subject: RE: Telephone headsets Chris, the CE marking indicates that the product complies with all applicable directives. The only two directives that might apply is the LV and EMC directives. However, the LVD does not apply since the working voltages are low. The EMC directive would apply if your equipment is likely to cause interference or likely to be susceptable to interference. I tend to believe that your equipment is not likely to cause interference, but it might be susceptable to magnetic fields. So some immunity requirements may apply. If so, your Declaration of Conformity would only claim compliance with the EMC Directive. If the EMC Directive does not apply, then no Declaration or CE marking is required. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: Chris K. Poore [mailto:chr...@percept.com] Sent: Friday, August 30, 2002 10:02 AM To: EMC-PSTC Subject: Telephone headsets We have some telephone headsets that we want to CE Mark, but are not sure what safety standard to use. Additionally, I don't see any category under the CE Marking directive that would be entirely applicable. The LVD seems most logical, except that the input voltage to the headsets is well below the 75DC, 50AC cutoff. The headsets will connect to an OEM audio amplifier that has been evaluated to the LVD, and seems to contain all the necessary isolation (we are not even selling the amplifier). The primary reason for wanting to CE Mark is because a competitor is doing it. Is there a safety standard that we should use that is specific to these telephone headsets for EU compliance? Thanks, Chris K. Poore Staff Compliance Engineer - Percept Technology Labs, Inc. 4735 Walnut #E Boulder, CO 80301 303-444-7480 ext. 113 303-444-1565 Fax mailto:chr...@percept.com http://www.percept.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Conducted Emissions---Sandy's Question and John's Question
Is this a telecommunications product? if so, then need DC conducted Emissions to new EU std. 300386. Done from 20khz to 30mhz. If product is ITE, then NO DC cond. is needed. Richard, -Original Message- From: Chris Maxwell [mailto:chris.maxw...@nettest.com] Sent: Wednesday, January 23, 2002 5:21 PM To: emc-p...@majordomo.ieee.org Subject: RE: Conducted Emissions---Sandy's Question and John's Question Hi guys, Remember, this is just my opinion. I work for a manufacturer, not a test lab; so this is a side job (a HUGE side job); not my life. For John: We do test the DC input of our rack-mount 48VDC products for conducted emissions. Many of our customers for these systems demand conducted emissions testing. The reasoning here is that these systems will operate from a DC mains which may operate many other products in the same rack or room. We use the same limits as for AC mains. However, we do not test the conducted emissions of the DC ports of our smaller products which run from wall-warts or bricks.For these products, we test the conducted emissions at the AC interface of the wall-wart or brick. For Sandy: When I test wall-warts for conducted emissions, I either plug them into the LISN directly or I use a short stub cable (about 6 long) made from Panel Components parts if I need to adapt the LISN output to a wall-wart with a non-US plug configuration. I then try to dress the wall-wart's cable in the configuration shown in the standard for dressing line cords. I'm sure there are other methods; but at least you have one opinion. 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: CE-test - Ing. Gert Gremmen - ce-marking and more... [SMTP:cet...@cetest.nl] Sent: Wednesday, January 23, 2002 2:10 PM To: John Stonier; emc-p...@majordomo.ieee.org Subject: RE: Conducted emission testing for EN55022 Hi John, EN 55022:1994 does not speak about DC power supplies. Other standards do. Normally the appropriate measurements are done on the AC supply side af any applied DC-power supply. The pitfall is that a good RF attenuating in the supply may hide the conducted emissions from your EUT, while another power supply may lead to serious spectrum problems. Your problem, because power supply manufactueres do not specify RF isolation classes. I suggest you to apply the test described using a basic transformer rectifier combination + simple stabilization circuit (if required), thereby minimizing attenuation and maximizing RF feedtrough. Take care to bridge the rectifier diodes with capacitors, otherwize thay might create interference themselves. Regards, Gert Gremmen, (Ing) Ce-test, qualified testing == Web presence http://www.cetest.nl/ CE-shop http://www.cetest.nl/ce_shop.htm /-/ Compliance testing is our core business /-/ == -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of John Stonier Sent: Wednesday, January 23, 2002 6:26 PM To: emc-p...@majordomo.ieee.org Subject: Conducted emission testing for EN55022 Hi folks My test lab's current interpretation of EN55022 is that DC Mains measurements are not required. Sections 56 specify measurements done on mains ports, but do not specify whether it applies to AC or DC mains. There is a reference in section nine that specifies conducted disturbance is measured between the phase lead and the reference ground, as well as the neutral lead and the reference ground. Does anyone know whether DC measurements are required for this standard? John Stonier File: Gert Gremmen.vcf --- 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
RE: EMI guard bands
Does anyone make Class A AND Class B products? if so, do you allow for a much smaller margin on the B since its approx. 10 db quieter than A to start with. or do you treat them equally. Also Oats site to Oats site can differ as much as +/- 4 db do to many factors. any comments? Richard, -Original Message- From: Gary McInturff [mailto:gary.mcintu...@worldwidepackets.com] Sent: Tuesday, December 18, 2001 1:19 PM To: Doug McKean; EMC-PSTC Discussion Group Subject: RE: EMI guard bands I hold with the 3 db under class B, as well as A. The only effective argument, in my mind, is the uncertainty of measurement issue. Beyond that I find that if I have 3 db everywhere my measurements next time down with that product or with one off the shelf have also been compliant. So if pragmatic repeated measurements is telling me I'm in then I am not going to spend the time and money to make even more sure that I am in. The goal is to not interfere with communications not to be invisible at all costs. If it ain't broke I'm not fixing it. Obviously, others disagree. By the way if a customer requests it, they get what they want, if they want to pay for it, and I have never rejected products with a 3 db band - and they haven't bitten me yet either. My couple cents Gary -Original Message- From: Doug McKean [mailto:dmck...@auspex.com] Sent: Monday, December 17, 2001 3:15 PM To: EMC-PSTC Discussion Group Subject: Re: EMI guard bands Tania Grant wrote: Amund, My minimum criteria and recommendation has always been at least 6dB. However, how many engineering managers, upon finding a 1.5 dB margin in their favor, rule ship it! nod Although in some markets, there are customers who require -6dB under the Class A limit. Although if I had it my way, I'd make it about -10dB under the limit. - 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. --- 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: Motor Drive Grounding Scheme
In typical testing of DC units, the two inputs are floating when doing for example: current checks and hipot to chassis ground. Yet, in a CO, the return lead is grounded, so you have a test lab condition ( return floating ) and a real condition, return tied to CO earth ground in service. The only thing unusual might be the delta in the ground connections, causing an impedance change, thus a voltage swing. In this case its 74vdc, so its hazardous, I would think doing appropriate fault testing @ UL would be sufficient. Just saying its unsafe and NO is not reasonable. Richard, -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Friday, October 19, 2001 3:45 AM To: 'Mark Haynes'; IEEE EMC-PSTC Discussion List (E-mail) Cc: Peter Deneault (E-mail); Tom Brenner; Doug Harris Subject: RE: Motor Drive Grounding Scheme Mark, If you think your product is safe, you must be able to prove it. For starters, I suggest you read UL60950. Somewhere in the Appendix, it allows one side of the input supply to telecommunication equipment intended for central office applications to be earthed. However, special markings andf instructions are required. Regret I do not have the time to commit for a full reasearch at this time. But, once you read the UL60950 standard, I am sure you will have a better case to explain to UL. Also, I recommend that you talk to an expert at UL rather than a low level engineer - you may try calling Jimmy Wong at UL Melville. 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 -Original Message- From: Mark Haynes [mailto:mhay...@dlsemc.com] Sent: Thursday, October 18, 2001 6:44 PM To: IEEE EMC-PSTC Discussion List (E-mail) Cc: Peter Deneault (E-mail); Tom Brenner; Doug Harris Subject: Motor Drive Grounding Scheme Greetings All, I work for a product safety consulting firm/test lab/agent. I am currently having some difficulties with UL relating to one of our customer's products. The grounding scheme of the products has become a barrier which has halted the planned testing. In our opinion, the engineering rationale behind this position is not very strong or clear. The products are small open-type stepper and servo motor drives (rated up to 6 A) which are intended to be used within another enclosure. They are powered by an 18 - 74 V dc external source which is supplied by the user. The drive output is a DC pulse width modulated waveform. UL 508C and UL 840 are the standards being used. The main issue is the fact that the DC - (common) input supply lead is connected internally to the input ground (PE) lead. UL has referenced UL 508C requirements (not really applicable to these particular products since we have agreed to use UL 840 for spacings) that indicate that spacings are required within the product between these two leads. This implies that this grounding scheme cannot be used. The manufacturer has indicated that the drives will not operate properly without this grounding connection. The product designers made this connection internally to prevent the common from floating above/below ground potential and for EMI purposes. The customer and my company do not agree with UL's position. One possible hazard UL stated was that the heatsink was connected to the grounded DC - (common) internal bus and could be electrically live. Since the heatsink is referenced to ground potential, it is not live during normal operation. If an internal fault does occur, the circuitry is designed such that the fault current will flow through the ground, as intended. In addition, a hint of possibly increasing the risk of shock was also mentioned. No one involved has been able to identify any real safety issues resulting from this grounding scheme. In order to address all potential safety hazards, we have recommended that testing be conducted to confirm compliance with the intent of the standards. This would hopefully show that the products are safe and that all foreseeable safety hazards (during normal and fault conditions) have been identified and minimized/eliminated. After weeks of research and discussions, we have not been able to convince UL that this grounding scheme should be allowed and that we should proceed with the testing. Does anyone know of any similar UL certified motor drives (or other similar DC powered products) that employ this grounding scheme? The closest examples we could find were AC powered products with DC ground referenced secondary
RE: 10/100 base interface in a plastic box
Jon, if your running high etherent freq. and the shield is NOT grounded, you might fail class A FCC/Cispr 22. Richard, -Original Message- From: Jon Keeble [mailto:j.kee...@fairlightesp.com.au] Sent: Wednesday, October 17, 2001 1:05 AM To: emc-p...@majordomo.ieee.org Subject: 10/100 base interface in a plastic box RJ45s come in shielded, unshielded, and shielded with integral magnetics (and probably other flavors as well). Has anybody got any suggestions / experience / whatever re the use of one or other of these parts in a product that will live in a plastic box, power by an external mains adapter / internal regulator. The intention is to use UTP cable. I've read Intel's appnotes regarding layout for PHY / Magnetics / RJ45. In a situation with no chassis to call chassis ground, I suspect the shield is irrelevant. However, I'm rather attracted to the 'integral magnetics' solution, and these all seem to have shields. Given that the planes are void under the connector I suppose that means this shield will just have to be 'not connected. Has anybody got a recommendation regarding voids under the 'integral magnetics' part? Regards Jon Keeble --- 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: Component ESD Immunity Testing
I would think speed of the energy source would be a critical factor. Does anyone have the information on Surge vs. ESD discharge for speed of pulse and duration. Richard, -Original Message- From: Chris Chileshe [mailto:chris.chile...@ultronics.co.uk] Sent: Tuesday, October 02, 2001 6:55 AM To: EMC-PSTC Subject: RE: Component ESD Immunity Testing Ravinder, I can attest to the 2kV ESD immunity of ICs because I have done such tests myself. I am now in the process of trying to raise the ESD immunity level to 4kV on one particular pin. Have you - or anyone else on this group - had any experience working with small surface mount varistors (EIA 0603 or 0805 size) specifically for ESD protection. I have only ever worked with large disc varistors primarily for surge protection (EN61000-4-5) and therefore a little sceptical about the effectiveness of an 0603 device at 4kV although I imagine they should be able to deal with ESD (EN 61000-4-2). Any advice? Regards - Chris -Original Message- From: Ravinder Ajmani [SMTP:ajm...@us.ibm.com] Sent: Monday, October 01, 2001 7:45 PM To: EMC-PSTC Subject:Re: Component ESD Immunity Testing I have been asked on several occasions to test some particular IC on the card, whenever there have been instances of IC failures during product manufacturing/testing. Most ICs are built to withstand an ESD event of 2 kV, and I have found this to be true in my tests. If IC happens to be OK then I try to improve the card design to reduce/eliminate the product failures. Regards, Ravinder PCB Development and Design Department IBM Corporation Email: ajm...@us.ibm.com *** Always do right. This will gratify some people and astonish the rest. . Mark Twain plaw...@west.net (Patrick Lawler) To: EMC-PSTC emc-p...@ieee.org Sent by: cc: owner-emc-pstc@majordom Subject: Re: Component ESD Immunity Testing o.ieee.org 10/01/2001 08:27 AM Please respond to plawler We have an engineer who did ESD testing once on the pins of ICs buried in a power supply assembly. The unit passed, and he thought it was a great way to show product robustness. However, when I asked him if he would redesign power supplies that failed his special test, he replied he wouldn't. Would _you_ redesign your system if it failed? Patrick Lawler plaw...@west.net On Mon, 1 Oct 2001 08:02:10 -0600 , Aschenberg, Mat matt.aschenb...@echostar.com wrote: Since all of you have your ESD hats on. Are there standards for testing of components on a pwb? There is some concern here that we should be testing individual components on the pwb. Thanks for your help. Mat Aschenberg --- 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 has been checked for all known viruses by Star Internet delivered through the MessageLabs Virus Scanning Service. For further information visit http://www.star.net.uk/stats.asp or alternatively call Star Internet for details on the Virus Scanning Service.
RE: Manufacturing Hipot Testing
I don't see where that proves anything ( 1/2 voltage testing) using voltage applicable to product is required. Testing for one second checks for shorts and miswiring or spacings that may have been decreased due to workmanship. Richard, -Original Message- From: raymond...@omnisourceasia.com.hk [mailto:raymond...@omnisourceasia.com.hk] Sent: Wednesday, August 22, 2001 10:26 AM To: emc-p...@majordomo.ieee.org Cc: owner-emc-p...@majordomo.ieee.org Subject: Re: Manufacturing Hipot Testing Dear All, I have read one BSEN standard suggesting not to perform hipot testing at the test voltage, 3kV, 1.25kV or 3.75kV in mass production. The reason is that it might introduce potential failure in future operation by the customer not immediate failure. It also suggests if hipot testing is done on production line, lower testing voltage, i.e., 1/2 of test voltage should be applied. I would like to have comments on this concern while doing hipot test on production line or other modern way to replace the hipot test on production line. Thanks and regards, .. Raymond Li Omni Source Asia Ltd. - Phone: +852-2542 5303 Email: raymond...@omnisourceasia.com.hk Fax: +852-2541 9067 John Woodgate j...@jmwa.demon.co.uk To: emc-p...@majordomo.ieee.org Sent by: cc: owner-emc-pstc@majordomSubject: Re: Manufacturing Hipot Testing o.ieee.org 22/08/01 01:39 a Please respond to John Woodgate I read in !emc-pstc that Doug McKean dmck...@corp.auspex.com wrote (in 001001c12a54$2b315f80$3e3e3...@corp.auspex.com) about 'Manufacturing Hipot Testing', on Tue, 21 Aug 2001: IMHO, if I were to address the initial question regarding manufactoring testing of a product bound for Europe - unless there were some severe national deviation differences from a similar type of US domestic approval of the product, I'd continue along with hi-pot testing just as if the product were bound for a domestic (US) market. Well, you have come to the right conclusion but for two wrong reasons. In Europe, there are no longer any 'national approvals' like the old SEMKO etc. There is ONLY the Low Voltage Directive, and the European Standards (ENs) that have been 'notified' in the Official Journal as providing evidence of compliance. However, most if not all of these ENs have *mandatory requirements* for 100% production-line testing (confusingly called 'routine testing'), including a 'hi-pot' test. It is entirely the responsibility of the manufacturer to ensure that the Declaration of Conformity for the product is true, and to do that he MAY, but does not have to, employ a test-house to produce a report and maybe an expensive certificate and grant permission, in return for more money, to apply a glamorous sticker to the product. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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,
RE: Conductive Coatings
Must worry about fire and electrical enclosure requirments as well. Depending on levels and components inside these 94v rating will vary. Richard, -Original Message- From: Doug McKean [mailto:dmck...@corp.auspex.com] Sent: Monday, August 20, 2001 7:22 PM To: EMC-PSTC Discussion Group Subject: Re: Conductive Coatings John, Yes. I've done it. But the info is dated a little. First, the plastic has to have it's own UL rating. For SELV this might involve V2 min. Not sure about that. Then, the mold house has to have it's own UL approval to do the molding. Then, the conductive coating must have it's own UL approval as an approved material. Then, the marriage of the coating and the coating has to have yet another UL approval. Then, the vendor who does the application of the coating to the plastic has to have yet another UL approval. Depending upon the coating being an oil base or water base, you'll get different ohm readings. The oil will be higher in general. Then, within the types of coating, be it oil or water based, there's differences in ohmage as well. I got nickel which was good for 0.5 ohm with a 7mil layer I believe. You can add more layers to lower the resistance. Silver and copper coating will be lower in resistance for the same thickness. Then, the conductive coating can't be used as a primary ground. Conductive coatings are also good for only one time use essentially. Removing and installing a cover several times with a conductive coating will jeopardize the integrity of the coating. It'll flake or simply wear off. So, it's best to use it with the understanding that once the cover is installed and fit in place, then it stays that way. I had very good results with it. It was getting through the safety aspects that proved difficult. This directly impacts the search effort for a vendor to use up front before you even start using it. Make sure to consult your safety approvals engineer at whatever NRTL you're using to fill you in on all the details specific to safety. Regards, Doug McKean --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on Virtual Conference Hall, --- 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 test suite for computers
Don't forget Telco Conducted Emissions is NOT required until at least 2003' Richard, -Original Message- From: Frazee, Douglas (Douglas) [mailto:dfra...@lucent.com] Sent: Friday, August 17, 2001 12:19 PM To: 'Pettit, Ghery'; 'Stuart Lopata'; emc Subject: RE: CE test suite for computers Ghery, I believe 61000-3-2, Class D is also required. Doug Frazee Regulatory Compliance Manager Lucent Technologies, Broadband Carrier Networks Access Technology Division InterNetworking Systems (301) 809-4415 (301) 352-4730 FAX dfra...@lucent.com -Original Message- From: Pettit, Ghery [mailto:ghery.pet...@intel.com] Sent: Thursday, August 16, 2001 4:39 PM To: 'Stuart Lopata'; emc Subject: RE: CE test suite for computers Stuart, For ITE the requirements are EN 55022:1994 (through 1 August 2003) and EN 55024:1998. If you wish to test to anything else, you need to go through a Competent Body and convince them that the alternate standards are adequate. Ghery Pettit Intel -Original Message- From: Stuart Lopata [mailto:stu...@timcoengr.com] Sent: Thursday, August 16, 2001 12:14 PM To: emc Subject: CE test suite for computers Any info about the test suite for computers (for commercial professional markets in EU) to meet the EMC directive for the CE mark? Also wondering if there is any collection of non-harmonized standards that are currently accepted for CE mark testing? to my knowledge, EMC testing for computers requires the following. (so far) EN 55022 for ITE equipment EN 61000 3-1 through 3-11 Sincerely, Stuart Lopata
current carrying conductors
Group, can you substitute one large wire 6 awg. ( handlles 63 amps. max ) for two smaller wires ( 10 awg. carries 32 amps. max. ) in Parallel. They would 1/2 the current and disperse heat better. The accepting screw terminal would allow for proper threading and tightness of connection. since you would have 2 ring lugs on one terninal instead of two. thank you, Richard, --- 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: http://www.rcic.com/ click on Virtual Conference Hall,
RE: Mexico question
You can get NOM exemption by meeting certain criteria for specialized equipment. Fast microprocessors,used in special places ( CO's) and not touched by non-technical people. this does not give you a NOM mark, but you get a letter stating its OK to ship into Mexico based on its specialized application. Richard, -Original Message- From: Alejandro Torrecilla Torregrosa [mailto:atorreci...@cetecom.es] Sent: Wednesday, August 08, 2001 6:59 AM To: EMC-PSTC1; Massey, Doug C. Subject: RE: Mexico question Hi Doug, NOM-001 includes electrical safety requirements and testing methods for type approval of household electronic apparatus as TVs, remote control, microwaves,... NOM-016 includes electrical safety requirements and testing methods for electronic apparatus for use in office as fax machines, photocopiers,... NOM-019 includes electrical safety requirements for data processing equipment as Laptops, notebooks, palmtops,..., their peripherals (printers, plotters, monitors,...) and equipment used to communicate such devices as routers, hubs,... In NOM-001 and NOM-016, the scope includes not only devices connected to AC Mains, but also conected to other kind of power supply as batteries. The scope of NOM-019 does not specify whether the devices are connected to the AC mains or not. In fact, it is not limited to devices connected to AC mains. Notice also that the standard is based on IEC65 and IEC950 whose scope is not limited to equipment connected to AC mains. As far as I understand, any ITE equipment must be NOM certified. The exception is when the device is going to be sold into another device (as modem cards) in which case the whole product requires NOM certification. Hope it helps, Alejandro -- De: Massey, Doug C.[SMTP:masse...@ems-t.com] Responder a:Massey, Doug C. Enviado el: martes 7 de agosto de 2001 23:20 Para: IEEE - PSTC FORUM (E-mail) Asunto: Mexico question Hello folks - Can anyone tell me if an ITE device that does not connect to AC Mains must be NOM certified in order to market the device in Mexico? One internet link says all ITE, another says AC Mains connected equipment - I'm confused. Does anyone have a link to or a list of regulated products? Thanks Doug Massey Safety Approvals Engineer LXE, Inc. Ph. (770) 447-4224 x3607 FAX (770) 447-6928 Visit our web home at http://www.lxe.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: http://www.rcic.com/ click on Virtual Conference Hall, --- 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: http://www.rcic.com/ click on Virtual Conference Hall,
RE: NEMA versus UL type - enviromental ratings
concerning -48vdc systems approved to UL 1950. Are thee any Field Approved quick disconnect connectors ( 2 position ) such as a Amp or Molex mate n'lock? does anyone know exact requirements to make this mate n' lock a field approved connector on -48vdc inputs? thanks Richard, -Original Message- From: Chris Wells [mailto:cdwe...@stargate.net] Sent: Tuesday, July 31, 2001 10:53 PM To: 'emc-pstc' Subject: NEMA versus UL type - enviromental ratings I'm looking for some feedback on NEMA versus UL type - environmental ratings for faceplates of panel mounted components. * First reality check - Are NEMA housing ratings = UL type, number by number? * Second - Can one self certify compliance to NEMA ratings? * Third - What is the difference between NEMA and UL type? I think of the NEMA rating as a proof of design test = rating while the UL type wants design verification at a deeper level? * Forth - Do any of you care about UL types? Our sister divisions design assemblies that use our components and use UL to inspect the design. That is where the pressure is coming from over NEMA. Our product line consists of components mounted to the door of an industrial type enclosure. A pollycarbonate faceplate frames an overlay that contains membrane pushbuttons, embedded LEDs and a window to see our alpha numeric or grahpic display. Between the faceplate and the enclosure panel is a gasket to help keep out moisture, dust etc. We can meet NEMA 1, 12, 3, 3R and for some designs 4 as long as the user installs the component in an enclosure of equal protection. We have tested our design at environmental extremes and it works well. Where it gets difficult is when UL wants an adhesive for the overlay that is specifically qualified to our particular plastic over the range of specified environmental withstand. They want more than a type test and follow up construction inspection but a rather lengthy performance test that goes beyond what we are prepared to do - as if we were the overlay manufactures. Part of the problem is that we have a special additive to the PC plastic - stainless steel fibers for ESD control. This is making for special combinations. So what do others do? Do you have overlay vendors that have coordinated recipe of components/adhesive etc. that works with pollycarbonate from -40 to 60C and comply to UL types (NEMA) types 1, 12, 3, 3R, or 4? Thanks for any FB you can give ! Chris Wells Sen. Des Eng. Cutler-Hammer Pittsburgh Pa well...@ch.etn.com mailto:well...@ch.etn.com
