[PSES] UL assessment of plastics - DC vs AC
Received a newsletter from UL. Said that they are looking into updating standards to account for DC di-electric withstand vs AC. I can understand that the physics of dc arcing and tracking could be different from ac, but why would the dc di-electric withstand be more onerous than ac? Perhaps they are mixing IR and di-electric withstand, which cannot be considered a similar test. Brian - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] UL assessment of plastics - DC vs AC
Possibly because standards provide an RMS level for AC dielectric and that never seems to be as high as the 'equivalent' DC dielectric test. Since dielectric strength test checks for sufficient clearances, the DC test would be tougher on solid insulation. Many standards say to us 1.41xAC for a DC test, presumably since any arc would occur at the peak of the AC test voltage. There is also some confusion about whether a leakage current limit should be imposed during dielectric tests. It depends on what you think you're checking during routine hi-pot. If creepage distances are compliant and you control what solid insulation is used as a critical component, I think you need only look for breakdown, not leakage. _ Ralph McDiarmid | Schneider Electric | Renewable Energies Business | CANADA | Regulatory Compliance Engineering From: Brian Oconnell oconne...@tamuracorp.com To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 11/30/2011 09:47 AM Subject: [PSES] UL assessment of plastics - DC vs AC Received a newsletter from UL. Said that they are looking into updating standards to account for DC di-electric withstand vs AC. I can understand that the physics of dc arcing and tracking could be different from ac, but why would the dc di-electric withstand be more onerous than ac? Perhaps they are mixing IR and di-electric withstand, which cannot be considered a similar test. Brian - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com __ This email has been scanned by the Symantec Email Security.cloud service. __ - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] UL assessment of plastics - DC vs AC
Brian, To be honest, who knows why UL does what they do? It appears that for years they have arranged test levels just to be different from IEC or whatever entity. Just my two cents, Michael Sundstrom OHD / TREQ Dallas Electronic Lab Analyst, EMC Lead 2170 French Settlement Rd, Suite B Dallas, Texas 75212 (214) 579 6312 (940) 390 3644c KB5UKT Albert Einstein once said, The definition of insanity is doing the same thing over and over again and expecting different results. -Original Message- From: Brian Oconnell [mailto:oconne...@tamuracorp.com] Sent: Wednesday, November 30, 2011 11:45 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] UL assessment of plastics - DC vs AC Received a newsletter from UL. Said that they are looking into updating standards to account for DC di-electric withstand vs AC. I can understand that the physics of dc arcing and tracking could be different from ac, but why would the dc di-electric withstand be more onerous than ac? Perhaps they are mixing IR and di-electric withstand, which cannot be considered a similar test. Brian - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] UL assessment of plastics - DC vs AC
Hi Brian: Hmm. I wonder if UL knows what UL knows. Mr. Flore Chiang of UL's Taiwan office has given several papers at the PSES Symposia on the physics of clearance, creepage, and solid insulation breakdown. These are classic papers and should be studied by all product safety professionals. Mr. Chiang has presented his papers to the IEC TC108 committee so that the committee can prepare insulation requirements that are in concert with the physics of electrically-caused breakdown. Without doing anything to improve my memory, I believe d.c. is easier on all of the insulations than is a.c. Mr. Chiang's papers discuss the differences and why. Richard Nute Product Safety Consultant Vancouver, Washington, U.S.A. -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Brian Oconnell Sent: Wednesday, November 30, 2011 9:45 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: UL assessment of plastics - DC vs AC Received a newsletter from UL. Said that they are looking into updating standards to account for DC di-electric withstand vs AC. I can understand that the physics of dc arcing and tracking could be different from ac, but why would the dc di-electric withstand be more onerous than ac? Perhaps they are mixing IR and di-electric withstand, which cannot be considered a similar test. Brian - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] UL assessment of plastics - DC vs AC
In message CEBCB02AF4974380921E3EC70FF83CBC@RichardHPdv6, dated Wed, 30 Nov 2011, Richard Nute ri...@ieee.org writes: Mr. Chiang has presented his papers to the IEC TC108 committee so that the committee can prepare insulation requirements that are in concert with the physics of electrically-caused breakdown. Doesn't TC 108 look to TC28 and TC109 for insulation requirements? Mr. Chiang might do well to contact them. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Some people who are peeling the finch of the financial crisis are thinking of biting a rook. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] UL assessment of plastics - DC vs AC
Hi John: Mr. Chiang drew his material from a number of sources, especially IEC sources, with attributions. Take a look at his bibliography. Best regards, Rich -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of John Woodgate Sent: Wednesday, November 30, 2011 1:38 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: UL assessment of plastics - DC vs AC In message CEBCB02AF4974380921E3EC70FF83CBC@RichardHPdv6, dated Wed, 30 Nov 2011, Richard Nute ri...@ieee.org writes: Mr. Chiang has presented his papers to the IEC TC108 committee so that the committee can prepare insulation requirements that are in concert with the physics of electrically-caused breakdown. Doesn't TC 108 look to TC28 and TC109 for insulation requirements? Mr. Chiang might do well to contact them. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Some people who are peeling the finch of the financial crisis are thinking of biting a rook. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
