RE: TNV Test Generator
Sam - Your post was no doubt sent before I replied to John Allen. FWIW, I'll try to add some clarity on the power cross testing. The power lines that are collocated with telecommunication lines are typically medium voltage. There are both induced voltages into and metallic power cross to the telecommunication lines. The primary protector at a building entrance limits the voltages available to do harm to 600Vrms (assumed sinusoidal). There might also be secondary protection on telecommunication lines that include supplemental overvoltage protection that limits the voltage downstream to even lesser levels. The 120V and 240V power cross tests are to simulate someone digging and tearing through both a branch circuit and a telecommunication line in a stroke. While much of the telecommunications infrastructure is buried, I hesitate to say most is. In most new construction since ~1970, perhaps earlier, it is. It certainly isn't in my parents' neighborhood; or probably most older neighborhoods and business districts, especially those that are less wealthy than others. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.com From: Sam Davis Sent: Thursday, December 12, 2002 7:56 AM In the US, aren't overhead power lines in the 10 kV range? Anyway, my point here is that the power line cross at the overhead poles won't just put 120V on the phone lines, but 10kV, likely incinerating the line. I'm not sure where the power line cross test is simulating, but it's not at the overhead poles. Besides that, most telephone wiring is buried. Just my 2C, Sam --- 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: TNV Test Generator
You're welcome, John. Yes, the test seems brutal. In North America, ringing is maximum 105Vrms, possibly riding on up to a -56.5Vdc wetted line (but not necessarily) and is limited to a few tens of mA. 120V/1200Ohms is still only 100mA, but that doesn't mean it won't cause grief at 3-5 times the US ringing current. However, the specification is for that source, IF there isn't one available to simulate the actual network. Sort of a poor man's networks simulator. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services 2000 Ringwood Ave. San Jose, CA 95131-1749 V: 408-904-2081 F: 408-904-2095 M: 408-234-3529 peter.tar...@sanmina-sci.com From: John Allen Sent: Thursday, December 12, 2002 8:18 AM Peter Thanks for that - quite a different background to how it seemed to read to me! But in that case it does seem a bit of a brutal test to apply to guard against a hazard caused solely by a telecomms-circuit source - surely a relatively low power source would be appropriate? Any idea why they did not more closely specify the equipment to be used? Regards Johh Allen --- 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: TNV Test Generator
Peter Thanks for that - quite a different background to how it seemed to read to me! But in that case it does seem a bit of a brutal test to apply to guard against a hazard caused solely by a telecomms-circuit source - surely a relatively low power source would be appropriate? Any idea why they did not more closely specify the equipment to be used? Regards Johh Allen -Original Message- From: Peter L. Tarver [mailto:peter.tar...@sanmina-sci.com] Sent: 12 December 2002 16:04 To: John Allen; emc-p...@majordomo.ieee.org Subject: RE: TNV Test Generator John, et al - No this is not the power cross test, which is described in Annex NAC of CSA/UL60950, third ed. This test is intended to simulate continuous ringing from the network, is akin the an SELV reliability test and, IIRC, was added to the base IEC 60950 standard at the behest of the French, due to limitations in their ability to guarantee cadenced ringing at all locations in their networks. Don Boroski is correct about test setup, though I'd use a variable autotransformer after an isolation transformer to set the voltage, rather than just taking it off of the line. As to real world power cross, on 15NON2000 I forwarded an unedited copy of a usenet posting containing a link to the Orange County on 15NOV2000, where power cross caused some small fires and fire fighters evacuated several homes. Because my post is not in the mindcruiser archive and the link in it to the newspaper article is now broken, I've placed a copy in the Info Pieces in the telecom general topics category on the mindcruiser site. The poster's remarks are also very interesting. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.com _ This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com * Copyright ERA Technology Ltd. 2002. (www.era.co.uk). All rights reserved. The information supplied in this Commercial Communication should be treated in confidence. No liability whatsoever is accepted for any loss or damage suffered as a result of accessing this message or any attachments. _ This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.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
RE: TNV Test Generator
John, et al - No this is not the power cross test, which is described in Annex NAC of CSA/UL60950, third ed. This test is intended to simulate continuous ringing from the network, is akin the an SELV reliability test and, IIRC, was added to the base IEC 60950 standard at the behest of the French, due to limitations in their ability to guarantee cadenced ringing at all locations in their networks. Don Boroski is correct about test setup, though I'd use a variable autotransformer after an isolation transformer to set the voltage, rather than just taking it off of the line. As to real world power cross, on 15NON2000 I forwarded an unedited copy of a usenet posting containing a link to the Orange County on 15NOV2000, where power cross caused some small fires and fire fighters evacuated several homes. Because my post is not in the mindcruiser archive and the link in it to the newspaper article is now broken, I've placed a copy in the Info Pieces in the telecom general topics category on the mindcruiser site. The poster's remarks are also very interesting. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.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
RE: TNV Test Generator
In the US, aren't overhead power lines in the 10 kV range? The power companies send power down the lines in kV (with relatively low current), and in the neighborhood of the customer, they have a large transformer which brings the voltage down to the 120 V range, with 100s of amps for that short run. The reason for this transmission scheme is that power (and power loss) is equal to I^2 R, so the higher the voltage, the lower the current necessary, and thus lower power loss over miles of resistance. Anyway, my point here is that the power line cross at the overhead poles won't just put 120V on the phone lines, but 10kV, likely incinerating the line. I'm not sure where the power line cross test is simulating, but it's not at the overhead poles. Besides that, most telephone wiring is buried. It is becoming increasingly rare to have telephone poles holding telephone wires. I'm not saying this is a reason to remove this requirement, because as long as the condition may exist in a normal or single fault (storm), there is a need to evaluate and/or test for it. Just my 2C, Sam -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of John Allen Sent: Thursday, December 12, 2002 2:43 AM To: emc-p...@majordomo.ieee.org Subject: RE: TNV Test Generator Hi Folks Is this not just the old UL/CSA (UL 1457/1950 etc) test to simulate a 120V power line falling onto the external POTS (etc)cable? In which case the test generator would be as per the relevant UL/CSA specs, and from memory that is similar to what has been suggested by Ken Javor or Don Borowski. This test was carried out because in North Americal most telephone cables and power cables are strung on poles - and the lines contact each other when the poles get knocked down by the awful weather (and/or awful drivers in some cases!) they often get in many states (Thank goodness I live in the UK - we don't get as much weather like that!) BTW, IMHO: a) Instead of a default of 120V, the test should specify the default to be application of the maximum nominal supply voltage of the equipment being tested, since that is likely to represent more closely the supply voltage on the power poles where the equipment is to be installed. [i.e. it would be 120V for N. America, but it would be 230V for Europe - and so on]. b) Even the latter does not address the problem that many overhead power distribution cables are 3-phase - so the test voltage should be the maximum phase-to-phase voltage in question. However, it has to said that the above changes would not go down well with suppliers of existing certified equipment - and I have no history to prove that the existing test is anything but adequate. Does anyone else know of real world problems that this test does not cover? John Allen Technical Consultant Electromagnetics, Safety and Reliability Group ERA Technology Ltd Cleeve Rd Leatherhead Surrey KT22 7SA Tel:+44 (0) 1372-367025 (Direct) +44 (0) 1372-367000 (Switchboard) Fax:+44 (0) 1372-367102 (Fax) -Original Message- From: don_borow...@selinc.com [mailto:don_borow...@selinc.com] Sent: 11 December 2002 22:19 To: emc-p...@majordomo.ieee.org Subject: Re: TNV Test Generator Am I missing something, or can you not just take a low impedance source of 120 VAC and simply add an external 1200 resistor in series with its output? Don Borowski Schweitzer Engineer Labs Pullman, WA FastWave bi...@fastwave.com@majordomo.ieee.org on 12/11/2002 12:55:45 PM Please respond to FastWave bi...@fastwave.com Sent by:owner-emc-p...@majordomo.ieee.org To:'emc-p...@majordomo.ieee.org' emc-p...@majordomo.ieee.org cc: Subject:TNV Test Generator Telecom - Product Safety Question: I am looking for a test generator per clause 2.3.5 of IEC60950 = a test generator is used that provides 120 V +/- 2 VAC at 50 or 60 Hz and has an internal impedance of 1200 ohms +/- 2%. Anybody have any input on a source to buy or a method to build such a device. It's the internal impedance aspect that's throwing me for a loop. Thanks for your time and input, Bill Bisenius EDD bi...@productsafet.com mailto:bi...@productsafet.com North Carolina - the natural disaster capital of the U.S. - last week's ice storm left us all without power, heat, or phones for several days (during 30 degree weather). Come to North Carolina and have your house smashed by falling ice covered trees (or hurricanes in the summer). --- 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
RE: TNV Test Generator
Hi Folks Is this not just the old UL/CSA (UL 1457/1950 etc) test to simulate a 120V power line falling onto the external POTS (etc)cable? In which case the test generator would be as per the relevant UL/CSA specs, and from memory that is similar to what has been suggested by Ken Javor or Don Borowski. This test was carried out because in North Americal most telephone cables and power cables are strung on poles - and the lines contact each other when the poles get knocked down by the awful weather (and/or awful drivers in some cases!) they often get in many states (Thank goodness I live in the UK - we don't get as much weather like that!) BTW, IMHO: a) Instead of a default of 120V, the test should specify the default to be application of the maximum nominal supply voltage of the equipment being tested, since that is likely to represent more closely the supply voltage on the power poles where the equipment is to be installed. [i.e. it would be 120V for N. America, but it would be 230V for Europe - and so on]. b) Even the latter does not address the problem that many overhead power distribution cables are 3-phase - so the test voltage should be the maximum phase-to-phase voltage in question. However, it has to said that the above changes would not go down well with suppliers of existing certified equipment - and I have no history to prove that the existing test is anything but adequate. Does anyone else know of real world problems that this test does not cover? John Allen Technical Consultant Electromagnetics, Safety and Reliability Group ERA Technology Ltd Cleeve Rd Leatherhead Surrey KT22 7SA Tel:+44 (0) 1372-367025 (Direct) +44 (0) 1372-367000 (Switchboard) Fax:+44 (0) 1372-367102 (Fax) -Original Message- From: don_borow...@selinc.com [mailto:don_borow...@selinc.com] Sent: 11 December 2002 22:19 To: emc-p...@majordomo.ieee.org Subject: Re: TNV Test Generator Am I missing something, or can you not just take a low impedance source of 120 VAC and simply add an external 1200 resistor in series with its output? Don Borowski Schweitzer Engineer Labs Pullman, WA FastWave bi...@fastwave.com@majordomo.ieee.org on 12/11/2002 12:55:45 PM Please respond to FastWave bi...@fastwave.com Sent by:owner-emc-p...@majordomo.ieee.org To:'emc-p...@majordomo.ieee.org' emc-p...@majordomo.ieee.org cc: Subject:TNV Test Generator Telecom - Product Safety Question: I am looking for a test generator per clause 2.3.5 of IEC60950 = a test generator is used that provides 120 V +/- 2 VAC at 50 or 60 Hz and has an internal impedance of 1200 ohms +/- 2%. Anybody have any input on a source to buy or a method to build such a device. It's the internal impedance aspect that's throwing me for a loop. Thanks for your time and input, Bill Bisenius EDD bi...@productsafet.com mailto:bi...@productsafet.com North Carolina - the natural disaster capital of the U.S. - last week's ice storm left us all without power, heat, or phones for several days (during 30 degree weather). Come to North Carolina and have your house smashed by falling ice covered trees (or hurricanes in the summer). --- 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 e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com
Re: TNV Test Generator
Am I missing something, or can you not just take a low impedance source of 120 VAC and simply add an external 1200 resistor in series with its output? Don Borowski Schweitzer Engineer Labs Pullman, WA FastWave bi...@fastwave.com@majordomo.ieee.org on 12/11/2002 12:55:45 PM Please respond to FastWave bi...@fastwave.com Sent by:owner-emc-p...@majordomo.ieee.org To:'emc-p...@majordomo.ieee.org' emc-p...@majordomo.ieee.org cc: Subject:TNV Test Generator Telecom - Product Safety Question: I am looking for a test generator per clause 2.3.5 of IEC60950 = a test generator is used that provides 120 V +/- 2 VAC at 50 or 60 Hz and has an internal impedance of 1200 ohms +/- 2%. Anybody have any input on a source to buy or a method to build such a device. It's the internal impedance aspect that's throwing me for a loop. Thanks for your time and input, Bill Bisenius EDD bi...@productsafet.com mailto:bi...@productsafet.com North Carolina - the natural disaster capital of the U.S. - last week's ice storm left us all without power, heat, or phones for several days (during 30 degree weather). Come to North Carolina and have your house smashed by falling ice covered trees (or hurricanes in the summer). --- 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: TNV Test Generator
It's bad form to answer a question with a question, but I will ask a very simple-minded question: Is the specified test generator anything different than the ac line (possibly through an isolation transformer) in series with 1200 Ohms? -- From: FastWave bi...@fastwave.com To: 'emc-p...@majordomo.ieee.org' emc-p...@majordomo.ieee.org Subject: TNV Test Generator Date: Wed, Dec 11, 2002, 2:55 PM Telecom - Product Safety Question: I am looking for a test generator per clause 2.3.5 of IEC60950 = a test generator is used that provides 120 V +/- 2 VAC at 50 or 60 Hz and has an internal impedance of 1200 ohms +/- 2%. Anybody have any input on a source to buy or a method to build such a device. It's the internal impedance aspect that's throwing me for a loop. Thanks for your time and input, Bill Bisenius EDD bi...@productsafet.com mailto:bi...@productsafet.com North Carolina - the natural disaster capital of the U.S. - last week's ice storm left us all without power, heat, or phones for several days (during 30 degree weather). Come to North Carolina and have your house smashed by falling ice covered trees (or hurricanes in the summer). --- 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
TNV Test Generator
Telecom - Product Safety Question: I am looking for a test generator per clause 2.3.5 of IEC60950 = a test generator is used that provides 120 V +/- 2 VAC at 50 or 60 Hz and has an internal impedance of 1200 ohms +/- 2%. Anybody have any input on a source to buy or a method to build such a device. It's the internal impedance aspect that's throwing me for a loop. Thanks for your time and input, Bill Bisenius EDD bi...@productsafet.com mailto:bi...@productsafet.com North Carolina - the natural disaster capital of the U.S. - last week's ice storm left us all without power, heat, or phones for several days (during 30 degree weather). Come to North Carolina and have your house smashed by falling ice covered trees (or hurricanes in the summer). --- 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
