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: Definitions - Safety Critical, Safety Circuit
My experience agrees with yours Gert - there is no simple formula to follow. In my early days as a PSE I tried to draw a flow-diagram of product safety assessment and decisions. On the first line I had about 20 options and each of those dropped down to about 20 more - many of which interlocked.after a couple of weeks I gave up. I believe there is a real danger when one tries to provide general guidance. There will always be exceptions - hence standardization and harmonization will (I believe) never satisfy all conditions. When I write product descriptions I deliberately over specify the safety aspects of critical components - or systems. There is one reason for this - to ensure that everyone on the project understands the impact of changing components. When the PD is cut down my the agency I send a file copy of my original for the manufacturing/design file. That way there is a history. (e.g. if I use an HB enclosure because the product if powered from and SELVEL PSU with current fold-back, then that goes into the general description AND the description of the PSU.) I get despondent reading some agency reports to do not include that level of detail - but a telephone call to the manufacturer usually gets the answer. I know that not everyone does writes descriptions the way I do and I am not suggesting that it is the best way (or ought to be standardized) - it just happens to work for me and my clients. Best regards Gregg P.O. Box 310 Reedville, Virginia 22539 Phone: (804) 453-3141 Fax: (804) 453-9039 Web:www.test4safety.com -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of CE-test - Ing. Gert Gremmen - ce-marking and more... Sent: Thursday, November 08, 2001 2:13 AM To: Doug McKean; EMC-PSTC Discussion Group Subject: RE: Definitions - Safety Critical, Safety Circuit Hi Dough, Group, I agree that is approach is much more simple to understand, but most definitions up to now have the problem of defining A LOT of components as safety critical. The safety critical parts need much more attention then just specification and name it. They need to be maintained in brand , type and material f.a. If an ECO (Engineering Change Order) is made, replacing a safety critical component needs re-assessment of the whole safety concept. Safety related components need however just fulfill their safety specs and they will do the job, and ordinary components may be replaced at will by the manufacturer by any other part that does the functional job. A similar reasoning can be made to measures, procedures, circuits (build from components) and construction. The approch i treid in an eralier mail made use of the double layer concept in safety (electrical mechanical chemical radiation heat and fire) to identify components. Those who bridge two layers of safety, or can invalidate the safety of a circuit are Safety Critical. (f.a. a cap that goes from hazardous voltageto an ungrounded accessible part) Those that bridge only one layer are Safety Related. (f.a. one of the two insulations in double insulation) Those that are redundant (from safety point of view) are ordinary components. What do you think of this: can this approach simplify the job ? 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 Doug McKean Sent: Thursday, November 08, 2001 4:07 AM To: EMC-PSTC Discussion Group Subject: Re: Definitions - Safety Critical, Safety Circuit Couldn't we just go to the front of the UL1950/60950 standard and agree that a safety critical part or device or circuit or construction is simply something used ... to prevent injury or damage due to: - Electric shock hazard - Energy hazards - Fire hazard - Mechanical hazard - Heat hazard - Radiation hazard - Chemical hazard ... 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: [Fwd: User Warning Signal Words]
From: Douglas Beckwith@MITEL on 11/08/2001 11:09 AM Sounds like it should be changed to either Alert, Note or similar. Does anyone know where this requirement comes from? Regards Doug Robert Macy m...@california.com on 11/07/2001 08:59:35 PM Please respond to Robert Macy m...@california.com To: Douglas Beckwith/Kan/Mitel@Mitel, David Heald davehe...@mediaone.net cc: emc-p...@majordomo.ieee.org, ni...@tsd.serco.com Subject: Re: [Fwd: User Warning Signal Words] Perhaps, it's time to utilize Alert instead of Warning for Class A compliance information. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: douglas_beckw...@mitel.com douglas_beckw...@mitel.com To: David Heald davehe...@mediaone.net Cc: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org; ni...@tsd.serco.com ni...@tsd.serco.com List-Post: emc-pstc@listserv.ieee.org Date: Wednesday, November 07, 2001 5:43 PM Subject: Re: [Fwd: User Warning Signal Words] From: Douglas Beckwith@MITEL on 11/07/2001 04:27 PM Hi All, If I may submit my two Canadian pesos worth. There is a US miltary handbook on technical writing that discusses the defintion of these words and how they should be used. Can't remember what it is off hand, but I will look it up and post it. These are the definitions that we use in our documentation. Here is a brief summary. CAUTION - Potential damage to the equipment, e.g. ESD or static WARNING - Potential minor injury or harm to the the user/maintainer. e.g sharp edges, corners etc DANGER - Potential major injury or death of the user/maintainer, e.g. exposed High voltage terminals. That being said, I have seen so many misuses and applications of these terms that deviate from the definitions, for example in the UK you are required to put an EMC Class A warning note in the documentation. In that case, I don't think that Class A emissions from an unintentional radiator are harmful, but that is another debate. Regards Doug Beckwith Mitel Networks --- 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: Definitions - Safety Critical, Safety Circuit
Hi Dough, Group, I agree that is approach is much more simple to understand, but most definitions up to now have the problem of defining A LOT of components as safety critical. The safety critical parts need much more attention then just specification and name it. They need to be maintained in brand , type and material f.a. If an ECO (Engineering Change Order) is made, replacing a safety critical component needs re-assessment of the whole safety concept. Safety related components need however just fulfill their safety specs and they will do the job, and ordinary components may be replaced at will by the manufacturer by any other part that does the functional job. A similar reasoning can be made to measures, procedures, circuits (build from components) and construction. The approch i treid in an eralier mail made use of the double layer concept in safety (electrical mechanical chemical radiation heat and fire) to identify components. Those who bridge two layers of safety, or can invalidate the safety of a circuit are Safety Critical. (f.a. a cap that goes from hazardous voltageto an ungrounded accessible part) Those that bridge only one layer are Safety Related. (f.a. one of the two insulations in double insulation) Those that are redundant (from safety point of view) are ordinary components. What do you think of this: can this approach simplify the job ? 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 Doug McKean Sent: Thursday, November 08, 2001 4:07 AM To: EMC-PSTC Discussion Group Subject: Re: Definitions - Safety Critical, Safety Circuit Couldn't we just go to the front of the UL1950/60950 standard and agree that a safety critical part or device or circuit or construction is simply something used ... to prevent injury or damage due to: - Electric shock hazard - Energy hazards - Fire hazard - Mechanical hazard - Heat hazard - Radiation hazard - Chemical hazard ... 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. attachment: Gert Gremmen.vcf
Re: Definitions - Safety Critical, Safety Circuit
Couldn't we just go to the front of the UL1950/60950 standard and agree that a safety critical part or device or circuit or construction is simply something used ... to prevent injury or damage due to: - Electric shock hazard - Energy hazards - Fire hazard - Mechanical hazard - Heat hazard - Radiation hazard - Chemical hazard 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: [Fwd: User Warning Signal Words]
Perhaps, it's time to utilize Alert instead of Warning for Class A compliance information. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: douglas_beckw...@mitel.com douglas_beckw...@mitel.com To: David Heald davehe...@mediaone.net Cc: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org; ni...@tsd.serco.com ni...@tsd.serco.com List-Post: emc-pstc@listserv.ieee.org Date: Wednesday, November 07, 2001 5:43 PM Subject: Re: [Fwd: User Warning Signal Words] From: Douglas Beckwith@MITEL on 11/07/2001 04:27 PM Hi All, If I may submit my two Canadian pesos worth. There is a US miltary handbook on technical writing that discusses the defintion of these words and how they should be used. Can't remember what it is off hand, but I will look it up and post it. These are the definitions that we use in our documentation. Here is a brief summary. CAUTION - Potential damage to the equipment, e.g. ESD or static WARNING - Potential minor injury or harm to the the user/maintainer. e.g sharp edges, corners etc DANGER - Potential major injury or death of the user/maintainer, e.g. exposed High voltage terminals. That being said, I have seen so many misuses and applications of these terms that deviate from the definitions, for example in the UK you are required to put an EMC Class A warning note in the documentation. In that case, I don't think that Class A emissions from an unintentional radiator are harmful, but that is another debate. Regards Doug Beckwith Mitel Networks --- 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
Us OLD guys used to think that digital was two levels of voltage - back then +5VDC and 0VDC. Thus DC could also mean Digital Computers. Way back then, the things did run relatively slow compared to these days so the AC signal you think of was only the step function of getting from one level to the next. In fact, we used to do that with switches on the front panel - manual clocks. These days, DC step functions happen faster than the settling time, leading to the appearance of AC looking signals. - Bill At 05:53 PM 11/07/2001 , eric.lif...@ni.com wrote: A question was posed as to when a digital I/O signal can be treated as a DC voltage source. My reaction is it must be treated as a AC signal. However, it could be operated such that the output changes state rather slowly. (This is a simple programmable I/O port for most any use.) But, the concept and some digging led me to another question. 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. To my knowledge, a rate of 200 Hz or less is explicitly saying that any interruption in power, even to shut it down on occasion, invokes the 28.4 V DC limit. (Silly interpretation, but that's what it says.) So friends, how continuous must DC be to qualify as continuous DC? 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. - British Prime Minister Tony Blair pointed to the victims of the Sept. 11 attacks on the World Trade Center and the Pentagon, and said the Taliban regime had no moral inhibition on slaughtering innocent people. There is no compromise possible with such people, no meeting of minds, no point of understanding with such terror, he said. There is just a choice: Defeat it or be defeated by it and defeat it we must. Whatever the dangers of the action we take, the dangers of inaction are far, far greater, he said. Bill Owsley, ows...@cisco.com 919) 392-8341 Compliance Engineer Cisco Systems 7025 Kit Creek Road POB 14987 RTP. NC. 27709 --- 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: [Fwd: User Warning Signal Words]
I read in !emc-pstc that douglas_beckw...@mitel.com wrote (in 85256afd.00759dd5...@kanmta01.software.mitel.com) about '[Fwd: User Warning Signal Words]', on Wed, 7 Nov 2001: for example in the UK you are required to put an EMC Class A warning note in the documentation. This is nothing specific to the UK, if you are referring to EN55022. -- 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: Have we lost something? was John Woodgate - RE: New EMC standards; now CISPR24/EN55024 query
Don't laugh!! those good ole days are still here. John Shinn, P.E. Manager, Laboratory Operations Sanmina Homologation Services -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of John Juhasz Sent: Thursday, November 01, 2001 12:47 PM To: 'CE-test - Ing. Gert Gremmen - ce-marking and more...'; emc-p...@majordomo.ieee.org Subject: RE: Have we lost something? was John Woodgate - RE: New EMC standards; now CISPR24/EN55024 query A . . . naiveté! I remember those days . . . Break it to him/her gently. John Juhasz Fiber Options Bohemia, NY -Original Message- From: CE-test - Ing. Gert Gremmen - ce-marking and more... [mailto:cet...@cetest.nl] Sent: Thursday, November 01, 2001 2:54 PM To: Ken Javor; Gregg Kervill; 'John Woodgate'; emc-p...@majordomo.ieee.org Subject: RE: Have we lost something? was John Woodgate - RE: New EMC standards; now CISPR24/EN55024 query You are right ??? May I add the following quoted part of an email inquiry we received today from one reputable USA manufacturer I received today in my mail box : QUOTE I apologize for the delay in responding back to you, but my boss is informing me that we simply have to fill out the EC Type Declaration of Conformity and put the label on it. The system will then be ok to send out. No documentation is needed until the system itself is questioned by the authorities or the customer. If we do get questioned, what sort of documentation will I need. Especially if I have not got the system officially tested. END QUOTE ?? This is maybe just because their own philosophy about safety and spectrum protection exceeds the requirements of current standards .. 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 Ken Javor Sent: Thursday, November 01, 2001 6:05 PM To: Gregg Kervill; 'John Woodgate'; emc-p...@majordomo.ieee.org Subject: Re: Have we lost something? was John Woodgate - RE: New EMC standards; now CISPR24/EN55024 query My opinion only. There was a time when the reputation of a manufacturer or business in general was a very important part of the success of that company, and the honesty and integrity of that company, extending to high quality products, was the major part of a good reputation. That is part of a free-market economy. The rationale behind immunity standards (indeed, gov't enforced emission standards) is that the free-market place does not work and it is more efficient to impose external political control. This is untrue a priori but becomes a self-fulfilling prophecy: once you impose rigid governmental standards industry-wide, there is nothing to be gained by exceeding the standard performance and everything to be gained by finding ways to meet these limits in the most cost-effective way. In effect, industry-wide standards tend to make what might have been a unique product into a commodity to be purchased from the lowest priced vendor. In this way, gov't imposed standards are are an assault on the integrity of the marketplace and ultimately justify their imposition by destroying the integrity that previously existed, while destroying the perception of individual integrity on the part of the consumer. Here is a simple example that works in the USA. Sometime in the 1930s the Federal Deposit Insurance Corporation was formed to insure bank deposits. Banks still like to boast about how strong they are, but for the average depositor the strength of the bank (the quality of their loans) is a moot point of little or no interest. If the bank goes bust, they are insured by the Fed. One bank looks pretty much like another to the average depositor. -- From: Gregg Kervill gkerv...@eu-link.com To: 'John Woodgate' j...@jmwa.demon.co.uk, emc-p...@majordomo.ieee.org Subject: Have we lost something? was John Woodgate - RE: New EMC standards; now CISPR24/EN55024 query Date: Thu, Nov 1, 2001, 9:20 AM I agree whole heartedly with John's point.And while deliberation may not always be a bad thing, a lack of immunity in an industrial computer must always be a bad thing, and very possibly a BAD THING! -- However it is not so much a lack of standards but a lack of will and commitment to Quality designs that I believe is the problem. Back in the dark ages - long ago - one of my design jobs was with a company making industrial photo-electric controls. We checked out emissions on all of our products using a LW/MW/VHF radio and a TV. We checked out susceptibility by wiring a BIG contactor as a buzzer and put x-y caps
