Re: Define Continuous DC Voltage
I read in !emc-pstc that eric.lif...@ni.com wrote (in of5431d5be.3bcd92cd-on86256aff.0061d...@natinst.com) about 'Define Continuous DC Voltage', on Fri, 9 Nov 2001: John Woodgate commented: [...] A digital signal that has one value at 0 V to ground and the other value at voltage V consists of a d.c. voltage of amplitude V/2 plus an a.c. voltage of (double) amplitude V/2. The frequency of the a.c. is irrelevant. [...] Per IEC 60950:1999, also in UL 1950:1995 (but not in '1010 or UL 31x1), D.C. Voltage is defined as: The average value of a voltage (as measured by a moving coil meter) having a peak-to-peak ripple not exceeding 10% of the average value. Note - Where peak-to-peak ripple exceeds 10% of the average value, the requirements related to peak voltage are applicable. I could not find the V/2 clause in 950. Perhaps its the TNV section of UL 1950:1995, clause 6.2.1.1, though it differs in that the divisor is not 2, but what I'd call a reference voltage, 42.4 V and others. Frequency here is limited to 100 Hz and below. It also repeats the 10% ripple criteria in Table 8. It isn't there, simply because 60950 is concerned with safety and not with defining what 'd.c.' is as a concept, which is what my text is about. The first part of the 60950 text is, however, entirely consistent with my text. Given a moving-coil meter with a long enough averaging time (much longer than the lowest frequency alternating voltage present), the meter will read V/2. The second part is not about the concept of 'd.c.', but entirely about how to treat, for safety purposes, a voltage that is part d.c. and part a.c., when the a.c. part exceeds 10%. It seems unclear (for us '1010 users) as to how continuous in time a DC voltage from 42.4 V DC Peak to 60 V DC Peak must be to avoid falling into the AC Peak limits, in an application that switches circuits on/off either randomly or periodically. It seems clear that the authors of 60950 did not take into account the case that troubles you. But, in Europe anyway, if your product is a '61010' product, you don't have to apply ANY of the provisions of 60950. Perhaps a simple voltage/frequency table derived from the Annex P leakage current model would allow our customers to use the full DC Voltage rating for sub 48 Hz switching rates, and specify a sliding scale of maximum rated voltage as the highest switching frequency goes up. That should be proposed to the new IEC TC108 as an improvement to IEC60950. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: Define Continuous DC Voltage
Sadly, I can't give that frequency; but I think I know the reasoning behind Eric's question... AC signals under 200Hz are especially dangerous to humans because AC currents really screw up our nervous system and cause death by heart attack at very low currents. It only takes milliamps of 60Hz AC current to kill a human being. On the other hand, people can withstand far more current from a DC source because it doesn't have the same effect on our nervous system. (Come on, who hasn't put a 9V battery on their tongue to test it out?) I think that this is the reasoning that the referenced standard uses to give two limits for AC and DC. My GUESS is that someone (who loved to torture living organisms) must have performed tests to figure out how DC current affected people (or monkeys, or rats... something). They then must have performed tests with different AC frequencies. Perhaps they even plotted a graph of hazardous voltage/current versus frequency. I would imagine that this is the type of data used by the IEC or any other safety organizationn to set hazardous voltage levels. Problem is...the standards don't give a graph or table of hazardous voltage vs. frequency, it just says DC and AC. Since we don't have access to the graph we really don't know what happens at ultra low frequencies. (Although I have a few rodents in my basement who are just asking to be test samples.) Of course, now there is the gray area of interpretation. (which keeps us all employed) For example, how would a safety engineer classify a 40V thermostat control signal (non current limited) with a five second hysteresis that prevents it from switching any faster than once every five seconds (0.2 Hz). Under normal conditions, this signal would switch once every couple of hours (0.00014Hz). Is this hazardous AC (after all it is 40V, and it does vary with time)? Or is it non-hazardous DC. Anybody want to tackle that question? It may help us to figure out Eric's initial problem. Remember to show your work...partial credit will be given :-) Just to show that I'm game... I'll take a stab. My opinion is that, if it can be proven that this signal will switch at a frequency no higher than 0.2 Hz under all normal and single fault conditions; then you have a non-hazardous DC signal. (Note that I'm not saying 0.2 Hz is the cutoff, it's probably higher.) OK... I've hung it out there. Either agree with it or refute it. Either way, we'll all learn something. 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: Ken Javor [SMTP:ken.ja...@emccompliance.com] Sent: Friday, November 09, 2001 1:22 PM To: Tania Grant; Doug McKean; EMC-PSTC Discussion Group Subject: Re: Define Continuous DC Voltage I'm probably not providing any assistance, but what is the purpose of the categorization of continuous dc vs. that rate of change where it is not considered continuous anymore? I don't think it should be tied to ability to deliver power to a load, which is in agreement with what Ms. Grant is saying below. Pure dc provides power and no information. A signal uses power to transmit information. If I have a security alarm sensor on a window which always sends a low-level dc until the window is broken then if I look at the physical parameters I could say that low-level signal was dc because it could be on for years, but its PURPOSE is to transmit information which makes it a signal. Actually any single-sided digital transmission (meaning between 0 Volts and some Vcc) is dc in the classical sense because dc means direct current, as opposed to alternating current which changes direction. In the sense which people in this exchange have been using the terminology it refers to how much time rate of change is allowed. But this is where the question as to purpose comes in. If the issue is crosstalk, a low-level audio or video signal with lots of rate of change is a much more benign source than a 48 Vdc source from which lots of switched CURRENT is drawn. A dc POTENTIAL does NOT imply direct CURRENT unless CE limits have been applied to loads. So the question that has to be answered first is what is the purpose of the discrimination implied by the term continuous. -- From: Tania Grant taniagr...@msn.com To: Doug McKean dmck...@corp.auspex.com, EMC-PSTC Discussion Group emc-p...@majordomo.ieee.org Subject: Re: Define Continuous DC Voltage Date: Thu, Nov 8, 2001, 9:47 PM Well now, Doug, how about the vast gray area in between? What if it is 1/50th of an amp? taniagr...@msn.com mailto:taniagr...@msn.com - Original Message -
[SI-LIST] Re: emi shielding
The mechanism for reflection is that em fields incident on a surface induce currents to flow such that the flow of current opposes the field which caused it. The material must have enough absorption and homogeneity (i.e., limited apertures) such that the induced currents remain on the side of the material where they were induced and do not re-radiate. That is the function of absorption and aperture control above 30 MHz. -- From: Wani, Vijay (V) vw...@dow.com To: 'ghery.pet...@intel.com' ghery.pet...@intel.com, 'emc-p...@majordomo.ieee.org' emc-p...@majordomo.ieee.org, 'si-l...@freelists.org' si-l...@freelists.org Subject: RE: [SI-LIST] Re: emi shielding Date: Fri, Nov 9, 2001, 11:52 AM all:thanks for your time and response. I understand the frequency range we worry about (30MHz - 2GHz), any metal (or metallized plastic) would be overkill and effect of apertures will be mostly determing factor for shielding effectiveness. but, the shielding mechanism of conductive metals (or metallized plastics) is mostly reflective rather than absorbtion. if we have a meterial with absorbtion shielding mechanism (in 30 MHz-2GHz frequency range), is there any advantage? i would guess, that will reduce antenna effect in the system. would appreciate any thoughts. vijay wani Dow Chemical -Original Message- From: Pettit, Ghery [mailto:ghery.pet...@intel.com] Sent: Friday, November 09, 2001 12:14 PM To: 'Wani, Vijay (V)'; 'emc-p...@majordomo.ieee.org'; 'si-l...@freelists.org' Subject: [SI-LIST] Re: emi shielding Vijay, The relative proportions are a function of frequency and the relative conductivity and relative permittivity of the material. The attached file is from a MathCAD 7.0 model that I put together a while back. The equations came from a Technit design guide published about 20 years ago. You will note that in the frequency range that we usually worry about almost any metal you might use is overkill. It is the apertures that create the problems. The example in the document is copper. I hope this helps. Ghery Pettit, NCE -Original Message- From: Wani, Vijay (V) [mailto:vw...@dow.com] Sent: Friday, November 09, 2001 7:36 AM To: 'emc-p...@majordomo.ieee.org'; 'si-l...@freelists.org' Subject: emi shielding hello: as we know, threre are two main component of shielding effectiveness. (Absorbtion and Reflection). is there any way to find out.. what percentage of overall shielding is due to absorbtion / reflection for a given material? thank you in advance. Vijay Wani Dow Chemical --- 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. -- To unsubscribe from si-list: si-list-requ...@freelists.org with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-requ...@freelists.org with 'help' in the Subject field List archives are viewable at: http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu --- 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. -- To unsubscribe from si-list: si-list-requ...@freelists.org with 'unsubscribe' in the Subject field or to
Re: Define Continuous DC Voltage
Doug et al, I think John realized that I was led down the path to UL 1310 and it's strange clause (continuous) in an attempt to quantify how/when a DC voltage becomes regarded to be an AC voltage in terms of hazard. I wasn't clear on that. Best Regards, Eric Lifsey Doug McKean dmck...@corp.auspex.coTo: EMC-PSTC Discussion Group m emc-p...@majordomo.ieee.org Sent by: cc: owner-emc-pstc@majordomSubject: Re: Define Continuous DC Voltage o.ieee.org 11/09/2001 12:26 PM Please respond to Doug McKean Well, to follow John's and Tania's comments ... For John, there wasn't any mention of hazardous in the original question. Only what would qualify as continuous DC. So, IMO, it doesn't matter what the frequency is as I stated with regards to an rms nor the level with regard to hazardous. The rms converts any signal dc or ac to a continuously delivered power to a load in terms of real power. Which brings me to Tania's question as in, whatever level you wish to consider. If it is 1/50th, then so be it. I thought it was an interesting question when I started considering heating effects with say fine pitch traces and such. Anywho, just my two cents ... Regards, Doug McKean --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: CISPR 22:1997
Jim, Israel has backed off on the telecom port conducted emissions portion of CISPR 22:1997. I haven't seen an official document, but my contact tells me that this has been done. Russia is still requiring the telecom port conducted emissions test, in spite of their regulatory folks being fully aware of the problems with it. Japan (VCCI) has delayed implementation until the problems can be sorted out. I'm not sure what Australia is doing at this time. Good luck. Ghery Pettit Intel -Original Message- From: jim.hulb...@pb.com [mailto:jim.hulb...@pb.com] Sent: Friday, November 09, 2001 11:19 AM To: emc-p...@ieee.org Subject: CISPR 22:1997 The European Union has postponed mandatory compliance with CISPR 22:1997 (EN 55022:1998) until 1 August 2003. This version of the standard includes the new requirement for conducted emissions on cables connected to telecommunications ports. Have other countries that require compliance with CISPR 22 (or some variation thereof) also postponed implementation of the 1997 version? My immediate concern is Australia. Any information members of this group can share is greatly appreciated. Jim Hulbert Senior Engineer - EMC Pitney Bowes --- 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: Define Continuous DC Voltage
I read in !emc-pstc that Doug McKean dmck...@corp.auspex.com wrote (in 000a01c1694c$1bc34ea0$3e3e3...@corp.auspex.com) about 'Define Continuous DC Voltage', on Fri, 9 Nov 2001: For John, there wasn't any mention of hazardous in the original question. Only what would qualify as continuous DC. What do you make of this extract from the original post, if it's not about hazardous voltages? QUOTE I consulted two UL standards: 508C and 3121-1 (and it's kin 3101/3111-1, all based on IEC 61010-1), both led me (by reference) to UL 1310 Class 2 Power Units. UL 1310 has a clause (14.2.2) which indicates that a DC interrupted at a rate of 200 Hz or less is limited to 24.8 V peak. In the same clause it mentions a continuous DC voltage of 60 V DC is permissible. UNQUOTE -- 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.
CISPR 22:1997
The European Union has postponed mandatory compliance with CISPR 22:1997 (EN 55022:1998) until 1 August 2003. This version of the standard includes the new requirement for conducted emissions on cables connected to telecommunications ports. Have other countries that require compliance with CISPR 22 (or some variation thereof) also postponed implementation of the 1997 version? My immediate concern is Australia. Any information members of this group can share is greatly appreciated. Jim Hulbert Senior Engineer - EMC Pitney Bowes --- 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: Define Continuous DC Voltage
Doug McKean commented: [...] Personally, I'd say when the source can deliver some sufficient level of real power (rms level of power). [...] The device in question can drive several milliamps on each channel, which I believe is a healthy shock. As a limited energy source it is unlikely to be a fire hazard. Since the model of the body is roughly 2,000 Ohms, that's a potential for up to 30 mA at 60 V DC and is probably rather painful. (There was a very good thread on fibrillation and other biological aspects of current about four [?] years ago on this list.) See Annex D of '950 for the leakage current model, which is also influenced by frequency. John Woodgate commented: [...] A digital signal that has one value at 0 V to ground and the other value at voltage V consists of a d.c. voltage of amplitude V/2 plus an a.c. voltage of (double) amplitude V/2. The frequency of the a.c. is irrelevant. [...] Per IEC 60950:1999, also in UL 1950:1995 (but not in '1010 or UL 31x1), D.C. Voltage is defined as: The average value of a voltage (as measured by a moving coil meter) having a peak-to-peak ripple not exceeding 10% of the average value. Note - Where peak-to-peak ripple exceeds 10% of the average value, the requirements related to peak voltage are applicable. I could not find the V/2 clause in 950. Perhaps its the TNV section of UL 1950:1995, clause 6.2.1.1, though it differs in that the divisor is not 2, but what I'd call a reference voltage, 42.4 V and others. Frequency here is limited to 100 Hz and below. It also repeats the 10% ripple criteria in Table 8. It seems unclear (for us '1010 users) as to how continuous in time a DC voltage from 42.4 V DC Peak to 60 V DC Peak must be to avoid falling into the AC Peak limits, in an application that switches circuits on/off either randomly or periodically. Perhaps a simple voltage/frequency table derived from the Annex P leakage current model would allow our customers to use the full DC Voltage rating for sub 48 Hz switching rates, and specify a sliding scale of maximum rated voltage as the highest switching frequency goes up. Thanks and Best Regards, Eric Lifsey Compliance Manager National Instruments --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: Define Continuous DC Voltage
Well, to follow John's and Tania's comments ... For John, there wasn't any mention of hazardous in the original question. Only what would qualify as continuous DC. So, IMO, it doesn't matter what the frequency is as I stated with regards to an rms nor the level with regard to hazardous. The rms converts any signal dc or ac to a continuously delivered power to a load in terms of real power. Which brings me to Tania's question as in, whatever level you wish to consider. If it is 1/50th, then so be it. I thought it was an interesting question when I started considering heating effects with say fine pitch traces and such. Anywho, just my two cents ... Regards, Doug McKean --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: Define Continuous DC Voltage
I'm probably not providing any assistance, but what is the purpose of the categorization of continuous dc vs. that rate of change where it is not considered continuous anymore? I don't think it should be tied to ability to deliver power to a load, which is in agreement with what Ms. Grant is saying below. Pure dc provides power and no information. A signal uses power to transmit information. If I have a security alarm sensor on a window which always sends a low-level dc until the window is broken then if I look at the physical parameters I could say that low-level signal was dc because it could be on for years, but its PURPOSE is to transmit information which makes it a signal. Actually any single-sided digital transmission (meaning between 0 Volts and some Vcc) is dc in the classical sense because dc means direct current, as opposed to alternating current which changes direction. In the sense which people in this exchange have been using the terminology it refers to how much time rate of change is allowed. But this is where the question as to purpose comes in. If the issue is crosstalk, a low-level audio or video signal with lots of rate of change is a much more benign source than a 48 Vdc source from which lots of switched CURRENT is drawn. A dc POTENTIAL does NOT imply direct CURRENT unless CE limits have been applied to loads. So the question that has to be answered first is what is the purpose of the discrimination implied by the term continuous. -- From: Tania Grant taniagr...@msn.com To: Doug McKean dmck...@corp.auspex.com, EMC-PSTC Discussion Group emc-p...@majordomo.ieee.org Subject: Re: Define Continuous DC Voltage List-Post: emc-pstc@listserv.ieee.org Date: Thu, Nov 8, 2001, 9:47 PM Well now, Doug, how about the vast gray area in between? What if it is 1/50th of an amp? taniagr...@msn.com mailto:taniagr...@msn.com - Original Message - From: Doug McKean Sent: Thursday, November 08, 2001 7:39 PM To: EMC-PSTC Discussion Group Subject: Re: Define Continuous DC Voltage eric.lif...@ni.com wrote: So friends, how continuous must DC be to qualify as continuous DC? Personally, I'd say when the source can deliver some sufficient level of real power (rms level of power). That is basically the definition of rms anyway. To make the point with two ridiculous examples, (1) if by shorting a 5 volt digital signal to ground you measure 1/100th amps of rms current, then I wouldn't call it DC. (2) if by shorting a 5 volt digital signal to ground you measure 10 amps or rms current, then I'd most definitely call it DC. But that's just me and my 2 cents worth. - 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: Products for evaluation
Sorry for the abrupt response but time is short and there are I believe there are serious issues here. If you would like to take some of these points off line please email me. A Class III LASER is dangerous! For UL/CSA you will need a FDA report. I have just completed just such a project. For CE Marking you might use that report (some may disagree because if it not of the EU). If you even need a CB Report you will need a IEC 825 (Number??) LASER REPORT An OPEN ??? are there interlocks? - processes? - operating instruction? The unit is definitely NOT a COMPONENT Nor can it ever be considered as such. Even if it was a component you WOULD NOT be able to sent it round the world. There are many differing requirements - I'll leave it to people better qualified (like John Woodgate) to give you the details (please John). P.O. Box 310, Reedville, Virginia 22539 USA Phone: (804) 453-3141 Fax: (804) 453-9039 Web: www.test4safety.com free eLearning Solutions If the product only was a component I would just send it around the world but it can function as a product by just adding a PC to a RS 232 port. How should I tread this product when sending it to US/Canada ? Can I just add a label on the product with a text like this: For evaluation purpose only ? And what about EU, the manufacturer is located in EU ? Best regards, Kim Boll Jensen Bolls Raadgivning Consultant in type approvals --- 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.
[SI-LIST] Re: emi shielding
Vijay, The relative proportions are a function of frequency and the relative conductivity and relative permittivity of the material. The attached file is from a MathCAD 7.0 model that I put together a while back. The equations came from a Technit design guide published about 20 years ago. You will note that in the frequency range that we usually worry about almost any metal you might use is overkill. It is the apertures that create the problems. The example in the document is copper. I hope this helps. Ghery Pettit, NCE -Original Message- From: Wani, Vijay (V) [mailto:vw...@dow.com] Sent: Friday, November 09, 2001 7:36 AM To: 'emc-p...@majordomo.ieee.org'; 'si-l...@freelists.org' Subject: emi shielding hello: as we know, threre are two main component of shielding effectiveness. (Absorbtion and Reflection). is there any way to find out.. what percentage of overall shielding is due to absorbtion / reflection for a given material? thank you in advance. Vijay Wani Dow Chemical --- 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. -- To unsubscribe from si-list: si-list-requ...@freelists.org with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-requ...@freelists.org with 'help' in the Subject field List archives are viewable at: http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu
[SI-LIST] Re: emi shielding
Vijay, Check out FloEMC, http://www.floemc.com/. You can have the software determine this by integrating the losses in the material, whether they are resistive or dielectric to find the absorption. Jeff Walden -- To unsubscribe from si-list: si-list-requ...@freelists.org with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-requ...@freelists.org with 'help' in the Subject field List archives are viewable at: http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu
RE: emi shielding
Absorbtion loss is given by A(dB) = 3.34 t (f(Mhz)Gu) where t = thickness in mils (sorry, my book is not metric based) G = conductivity relative to copper (G = 1 for copper) u = relative permeability to vacuum Reflection loss is given by R(dB) 20 log [(K_1)^2/4K] which is approx 20 log [Z(w)/4Z(b)] for K10 where Zw is the wave impedance and Zb is the surface impedance. For plane waves R(dB) = 108 + 10 log [G/uf(MHZ)] All this is from EMC Handbook, Vol 3, Don White Consultants, 1973. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: Wani, Vijay (V) [mailto:vw...@dow.com] Sent: Friday, November 09, 2001 10:36 AM To: 'emc-p...@majordomo.ieee.org'; 'si-l...@freelists.org' Subject: emi shielding hello: as we know, threre are two main component of shielding effectiveness. (Absorbtion and Reflection). is there any way to find out.. what percentage of overall shielding is due to absorbtion / reflection for a given material? thank you in advance. Vijay Wani Dow Chemical --- 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.
emi shielding
hello: as we know, threre are two main component of shielding effectiveness. (Absorbtion and Reflection). is there any way to find out.. what percentage of overall shielding is due to absorbtion / reflection for a given material? thank you in advance. Vijay Wani Dow Chemical --- 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.
Products for evaluation
Hi all A customer of mine have a product which have a controller unit with mains power and an open Class 3B laser unit. The product will normally be regarded as a component for build-in but it can also be used by students for laser experiments etc. as it is. The product is not in production yet but is ready for shipment in a small quantity (around 25 units). If the product only was a component I would just send it around the world but it can function as a product by just adding a PC to a RS 232 port. How should I tread this product when sending it to US/Canada ? Can I just add a label on the product with a text like this: For evaluation purpose only ? And what about EU, the manufacturer is located in EU ? Best regards, Kim Boll Jensen Bolls Raadgivning Consultant in type approvals --- 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: Most recent publications
I had a quick look at the ETSI site. The following link has jumps to more information. The publications search seems to have narrow date windows. http://portal.etsi.org/Portal_Common/home.asp It may give you the information you need. Santa Claus has friends at ETSI. Best regards, Geoff Lister Senior Engineer Motion Media Technology Ltd., Bristol, UK. http://www.motion-media.com -Original Message- From: am...@westin-emission.no [mailto:am...@westin-emission.no] Sent: 09 November 2001 08:42 To: emc-p...@majordomo.ieee.org Subject: Most recent publications Hi all, I like the IEC page Most recent publications on http://www.iec.ch/cgi-bin/procgi.pl/www/iecwww.p?wwwlang=ewwwprog=newpub.p Not because it gives you a lot of details regarding the standards, but it keeps you informed about new publications. Well, I had hoped we could download the standards, but I realize that Santa Claus is not working in IEC. My question is : Do ESTI have a similar page on the WEB, describing new publications day-by-day, just like IEC are doing ? Best regards Amund Westin, Oslo/Norway snip --- 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.
Most recent publications
Hi all, I like the IEC page Most recent publications on http://www.iec.ch/cgi-bin/procgi.pl/www/iecwww.p?wwwlang=ewwwprog=newpub.p Not because it gives you a lot of details regarding the standards, but it keeps you informed about new publications. Well, I had hoped we could download the standards, but I realize that Santa Claus is not working in IEC. My question is : Do ESTI have a similar page on the WEB, describing new publications day-by-day, just like IEC are doing ? Best regards Amund Westin, Oslo/Norway --- 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: Define Continuous DC Voltage
I read in !emc-pstc that Doug McKean dmck...@corp.auspex.com wrote (in 000b01c1689b$3fc85e00$3e3e3...@corp.auspex.com) about 'Define Continuous DC Voltage', on Thu, 8 Nov 2001: So friends, how continuous must DC be to qualify as continuous DC? Personally, I'd say when the source can deliver some sufficient level of real power (rms level of power). That is basically the definition of rms anyway. To make the point with two ridiculous examples, (1) if by shorting a 5 volt digital signal to ground you measure 1/100th amps of rms current, then I wouldn't call it DC. (2) if by shorting a 5 volt digital signal to ground you measure 10 amps or rms current, then I'd most definitely call it DC. But that, while probably important, is not about 'continuity'. In any case, IEC/EN60950 already defines what voltages and currents are hazardous in various ways. A digital signal that has one value at 0 V to ground and the other value at voltage V consists of a d.c. voltage of amplitude V/2 plus an a.c. voltage of (double) amplitude V/2. The frequency of the a.c. is irrelevant. I think the cited standards were written while this concept was not loaded into memory. (;-) -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: Define Continuous DC Voltage
Well now, Doug, how about the vast gray area in between? What if it is 1/50th of an amp? taniagr...@msn.com - Original Message - From: Doug McKean Sent: Thursday, November 08, 2001 7:39 PM To: EMC-PSTC Discussion Group Subject: Re: Define Continuous DC Voltage eric.lif...@ni.com wrote: So friends, how continuous must DC be to qualify as continuous DC? Personally, I'd say when the source can deliver some sufficient level of real power (rms level of power). That is basically the definition of rms anyway. To make the point with two ridiculous examples, (1) if by shorting a 5 volt digital signal to ground you measure 1/100th amps of rms current, then I wouldn't call it DC. (2) if by shorting a 5 volt digital signal to ground you measure 10 amps or rms current, then I'd most definitely call it DC. But that's just me and my 2 cents worth. - 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.
