RE: Clause 2.10.3.3 of EN 60950-1:2006
All - Let no one feel they can not impact standards development, even without attending meetings. After a few e-mails and one telephone call, I submit the following. §2.10.3.3: A very simple edit to the text is being proposed to make the application of Table 2K and 2L clear. Specifically (asterisks surrounding added text): b) if the peak working voltage exceeds the peak value of the ac mains supply voltage, the minimum clearance is the sum of the following two values: * the minimum clearance from Table 2K **using a value for the peak working voltage that is equal to the peak of the ac mains supply voltage**; and * the appropriate additional clearance from Table 2L **using the value of the peak working voltage**. A couple of other insulation issues discussed in this forum were also discussed. LINEAR INTERPOLATION: Linear interpolation for the values of Creepage Distance smaller than 0.1 mm, are required to round up to the nearest 0.1 mm. For values in Table 2N for smaller than 0.1 mm (those for boards), an editorial change will make it clear that, if rms working voltage falls between two values, use the next higher Creepage Distance *or* round up to the nearest 0.1 mm. As it turns out, this was already in the works. CLEARANCES TRUMPING CREEPAGE DISTANCES: The last point (on interpolation) may be unworthy of debate, considering that, with the addition of the small Creepage Distances allowed for boards, the conflict that no Creepage Distance may be smaller than the otherwise required Clearance will not be resolved soon. Those who may recall or wish to look into the matter on their own, will find that the smallest Clearances anywhere in the standard are 16×, 8× and 4× (Tables 2K, 2M and G.2, respectively) larger than the smallest Creepage Distance in Table 2N. As it turns out, the very presence of the two columns for boards in Table 2N is being debated, with advocates to remove them and to keep them. As represented to me, at issue is the practical concern of being able to measure small Creepage Distances. I have pointed out that there are freeware and shareware software tools available, if the test houses are too frugal to purchase the readily available optical instruments. Finally, in the columns in Table 2N applicable to boards, for Pollution Degree 2, Material Group IIIb was intentionally left out. I asked for a note similar to the note already in the Conditions to Table 2N for Material Group IIIb in Pollution Degree 3. No response was given for this item, so it may be left hanging and accepted as understood. Regards, Peter L. Tarver, PE ptar...@ieee.org CONFIDENTIALITY This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof. ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or any other person or entity. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email __
RE: Clause 2.10.3.3 of EN 60950-1:2006
Hi Peter, I think the way you read the standard is the most natural reading, but the final answer isn't really clear from the standard alone. It would seem that the penalty for the extra volt of peak voltage (from 420 V to 421 V) is double what it should be (0.2 mm vs. 0.1mm). If you get feedback from the US TAG member on this issue, please share! Scott Aldous Compliance Engineer Advanced Energy Tel: 970-407-6872 Fax: 970-407-5872 From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Tarver, Peter Sent: Friday, June 29, 2007 2:01 PM To: emc-p...@ieee.org Subject: RE: Clause 2.10.3.3 of EN 60950-1:2006 From: Tarver, Peter Sent: Friday, June 29, 2007 12:00 PM Man, did I mess this up. See my corrections, below. For an AC MAINS SUPPLY not exceeding 300 V r.m.s. (420 V peak): b) if the PEAK WORKING VOLTAGE exceeds the peak value of the AC MAINS SUPPLY voltage, ... If we have an ac mains rated up to 300 V (420 Vpk), and we measure a peak voltage across a piece of insulation in the primary circuit at 421 Vpk ... ... the minimum CLEARANCE is the sum of the following two values: * the minimum CLEARANCE from Table 2K; and * the appropriate additional CLEARANCE from Table 2L What then have is: Vb = 421 Vpk, clearance = 4.1 mm (interpolating and rounding up to the nearest 0.1 mm) + 0.1 mm (interpolating and rounding up to the nearest 0.1 mm) = 4.2 mm. I'm going through a few test cases for my own benefit and I am in the process of writing a US TAG member to TC108 that is already addressing clearance and creepage distances problems in the 2nd ed. Regards, Peter L. Tarver, PE ptar...@ieee.org CONFIDENTIALITY This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof. ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or any other person or entity. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email __
RE: Clause 2.10.3.3 of EN 60950-1:2006
From: Tarver, Peter Sent: Friday, June 29, 2007 12:00 PM Man, did I mess this up. See my corrections, below. For an AC MAINS SUPPLY not exceeding 300 V r.m.s. (420 V peak): b) if the PEAK WORKING VOLTAGE exceeds the peak value of the AC MAINS SUPPLY voltage, ... If we have an ac mains rated up to 300 V (420 Vpk), and we measure a peak voltage across a piece of insulation in the primary circuit at 421 Vpk ... ... the minimum CLEARANCE is the sum of the following two values: * the minimum CLEARANCE from Table 2K; and * the appropriate additional CLEARANCE from Table 2L What then have is: Vb = 421 Vpk, clearance = 4.1 mm (interpolating and rounding up to the nearest 0.1 mm) + 0.1 mm (interpolating and rounding up to the nearest 0.1 mm) = 4.2 mm. I'm going through a few test cases for my own benefit and I am in the process of writing a US TAG member to TC108 that is already addressing clearance and creepage distances problems in the 2nd ed. Regards, Peter L. Tarver, PE ptar...@ieee.org CONFIDENTIALITY This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof. ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or any other person or entity. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email __
RE: Clause 2.10.3.3 of EN 60950-1:2006
From: Aldous, Scott Sent: Friday, June 29, 2007 9:48 AM Looking over the two versions of the standard, I can see that you're correctly interpreting the 1st ed., but the 2nd ed. text changed things all over the place in the insulation area. I don't know if that was MT2's intent, but that's the effect of either their intent or bad standards writing leading to misinterpretations. At the risk of the wrath of the Gods on Mount Copyright, I'm going to directly quote the standard, so we can better review the text and work through an exercise, based on the 2nd ed. text. For an AC MAINS SUPPLY not exceeding 300 V r.m.s. (420 V peak): a) if the PEAK WORKING VOLTAGE does not exceed the peak value of the AC MAINS SUPPLY voltage, minimum CLEARANCES are determined from Table 2K; That seems plain enough; if the peak voltage across the insulation being evaluated is less than or equal to the peak voltage of the ac mains, only Table 2K applies. Let's say we're at 420 Vpk: Va = 420 Vpk, clearance = 4.0 mm for RI A minor rearrangement: For an AC MAINS SUPPLY not exceeding 300 V r.m.s. (420 V peak): b) if the PEAK WORKING VOLTAGE exceeds the peak value of the AC MAINS SUPPLY voltage, ... If we have an ac mains rated up to 300 V (420 Vpk), and we measure a peak voltage across a piece of insulation in the primary circuit at 421 Vpk ... ... the minimum CLEARANCE is the sum of the following two values: * the minimum CLEARANCE from Table 2K; and * the appropriate additional CLEARANCE from Table 2L What then have is: Vb = 421 Vpk, clearance = 4.1 mm (interpolating and rounding up to the nearest 0.1 mm) + 0.6 mm (interpolating and rounding up to the nearest 0.1 mm) = 4.7 mm. I'm saying that the 2nd ed. is looking only at the peak voltage across the insulation as the fulcrum where one derives the appropriate clearance and sets aside the (clearer) method from the 1st ed. [SCOTT]: It would seem that we may be on the same page, though perhaps I did not explain myself clearly after all. So in the end, I still feel the conclusion offered by Nick's customer is not correct. Do you agree? I'm not completely sure that you do - it seems the point we still may disagree on is what peak voltage to use when applying table 2K to the point in Nick's circuit where the 840Vpk is present. If we are to take an historical perspective, Nick's customer *might* be incorrect and what we see in the 2nd ed. is the result of bad standards writing. However, considering the present text in a vacuum, Nick's customer's interpretation seems correct. Considering all of the other bleepity-bleep bleeps MT2 threw into the clearance and creepage requirements for the 2nd ed., you may be entirely right and Nick's customer wrong. The more I think about it, the more I think MT2 blew it. Regards, Peter L. Tarver, PE ptar...@ieee.org CONFIDENTIALITY This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof. ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or any other person or entity. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email
RE: Clause 2.10.3.3 of EN 60950-1:2006
Thanks Peter for your comments. Mine interspersed below. Scott Aldous Compliance Engineer Advanced Energy Tel: 970-407-6872 Fax: 970-407-5872 I wonder what peak working voltage should be used in table 2K - the actual peak voltage or the peak voltage based on the mains rms voltage? [PETER]: If you look at the leading ¶s in §2.10.3.3, you can see answer to that question. [SCOTT]: I'm not sure I follow what you mean. [PETER]: Table 2K is written assuming the peak voltage is exclusively from the ac mains. [SCOTT]: Exactly. Which is why I wonder if only the AC mains peak voltage should be used when deriving a clearance from this table (except for the last line of 2.10.3.3 which provides the exception). [PETER]: The other peak working voltages (nee: peak repetitive voltages) are from primary circuit monkey business, but isn't new (see 60950-1, 1st ed, §2.10.3.2, Tables 2H and 2J). [SCOTT]: Correct, and the previous standard specifically states in 2.10.3.2 (first 2 dashes) that the clearance is the sum of: - the minimum CLEARANCE value from table 2H for a WORKING VOLTAGE equal to the AC MAINS SUPPLY voltage; and - the appropriate additional CLEARANCE value from table 2J. Pay particular attention to the verbiage between the asterisks that I added. [PETER]: It depends on where the insulation is that the working voltage is measured across. Before the rectifier in a SMPS, which is similar to your example, it would be appropriate to ignore Table 2L altogether. In this case, the minimum Clearance for Reinforced Insulation is 4.0 mm. Much deeper into an SMPS from the rectifier, peak repetitive voltage crop up that exceed those from the ac mains. [SCOTT]: This seems like a better explanation than I have offered, but much the same as my own thoughts. I don't believe this contradicts the interpretation I have offered. In general, one would expect to find a peak voltage higher than the standard mains peak only a bit deeper into the circuitry. I would assume that this is the case for Nick's example. Where such peaks exist, it would make sense to add the additional clearance from table 2L to the base clearance from table 2K based on the mains peak voltage only. In this case 4.0mm + 1.2mm for a total of 5.2mm. Then, for the 400V mains, one would use table 2K only, based on 840Vpk, giving 6.4mm for reinforced. [PETER]: But where is the 840 Vpk coming from and where is it measured? Not the ac mains, which for a 400 V supply is 566 Vpk, leading to a or 4.8 mm interpolated value (or 6.4 mm noninterpolated). Assuming the 840 Vpk is in the SMPS somewhere, 6.4 mm would apply only where it's present. [SCOTT]: I think your interpretation above is correct, and coincides with what I have offered. More intuitive, but is this the proper interpretation? [PETER]: I'd say not improper, but maybe not complete. [SCOTT]: It would seem that we may be on the same page, though perhaps I did not explain myself clearly after all. So in the end, I still feel the conclusion offered by Nick's customer is not correct. Do you agree? I'm not completely sure that you do - it seems the point we still may disagree on is what peak voltage to use when applying table 2K to the point in Nick's circuit where the 840Vpk is present. Regards, Peter L. Tarver, PE ptar...@ieee.org CONFIDENTIALITY This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof. ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or any other person or entity. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to:
RE: Clause 2.10.3.3 of EN 60950-1:2006
From: Aldous, Scott Sent: Friday, June 29, 2007 8:56 AM Bummer - I was referring to an older version of the IEC standard (60950-1:2001). I kinda thought something like that. With the 2nd ed of IEC 60950-1, the clearance and creepage distances went through a huge rewrite. I wonder what peak working voltage should be used in table 2K - the actual peak voltage or the peak voltage based on the mains rms voltage? If you look at the leading ¶s in §2.10.3.3, you can see answer to that question. It doesn't seem to make sense that if table 2K already takes into account higher peak voltages than one normally has, that one would need to add additional clearance per table 2L. Table 2K is written assuming the peak voltage is exclusively from the ac mains. The other peak working voltages (nee: peak repetitive voltages) are from primary circuit monkey business, but isn't new (see 60950-1, 1st ed, §2.10.3.2, Tables 2H and 2J). If one assumes nominal peak voltage on 230V of 230*1.414 = about 325V, ignoring interpolation and using peak of 420, then one obtains 4.0mm for reinforced plus the 1.2 from table 2L for a total of 5.2mm. It depends on where the insulation is that the working voltage is measured across. Before the rectifier in a SMPS, which is similar to your example, it would be appropriate to ignore Table 2L altogether. In this case, the minimum Clearance for Reinforced Insulation is 4.0 mm. Much deeper into an SMPS from the rectifier, peak repetitive voltage crop up that exceed those from the ac mains. Then, for the 400V mains, one would use table 2K only, based on 840Vpk, giving 6.4mm for reinforced. But where is the 840 Vpk coming from and where is it measured? Not the ac mains, which for a 400 V supply is 566 Vpk, leading to a or 4.8 mm interpolated value (or 6.4 mm noninterpolated). Assuming the 840 Vpk is in the SMPS somewhere, 6.4 mm would apply only where it's present. More intuitive, but is this the proper interpretation? I'd say not improper, but maybe not complete. Regards, Peter L. Tarver, PE ptar...@ieee.org CONFIDENTIALITY This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof. ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or any other person or entity. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email __
RE: Clause 2.10.3.3 of EN 60950-1:2006
Bummer - I was referring to an older version of the IEC standard (60950-1:2001). Everyone, please ignore my previous post (just when you get comfortable with a standard, they go and change it!). I assumed secondary circuit because of the table number (per the old standard). Now, looking at the correct standard (hopefully!)... I wonder what peak working voltage should be used in table 2K - the actual peak voltage or the peak voltage based on the mains rms voltage? It doesn't seem to make sense that if table 2K already takes into account higher peak voltages than one normally has, that one would need to add additional clearance per table 2L. If one assumes nominal peak voltage on 230V of 230*1.414 = about 325V, ignoring interpolation and using peak of 420, then one obtains 4.0mm for reinforced plus the 1.2 from table 2L for a total of 5.2mm. Then, for the 400V mains, one would use table 2K only, based on 840Vpk, giving 6.4mm for reinforced. More intuitive, but is this the proper interpretation? Scott Aldous Compliance Engineer Advanced Energy Tel: 970-407-6872 Fax: 970-407-5872 From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Tarver, Peter Sent: Friday, June 29, 2007 9:36 AM To: srichard...@blackwood-labs.co.uk; emc-p...@ieee.org Subject: RE: Clause 2.10.3.3 of EN 60950-1:2006 Good morning, Scott. From: Aldous, Scott Sent: Friday, June 29, 2007 8:18 AM Table 2L is for minimum creepage distances, not clearance. I don't know which version of EN 60950-1 you're referring to, but in the 2006 version, Table 2L most certainly applies to clearances. I see nothing in 60950-1 that indicates values from table 2L are to be added to values from table 2K for clearances in secondary circuits. Maybe I missed something. Where were secondary circuits mentioned in the OP? Since Table 2K is for clearances in primary circuits and between primary and secondary circuits, and that all references were to mains voltages (as far as I could tell), I don't think clearances _in_ secondary circuits (which would invoke Table 2M) are involved in the question. Regards, Peter L. Tarver, PE ptar...@ieee.org CONFIDENTIALITY This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof. ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or any other person or entity. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings
RE: Clause 2.10.3.3 of EN 60950-1:2006
Good morning, Scott. From: Aldous, Scott Sent: Friday, June 29, 2007 8:18 AM Table 2L is for minimum creepage distances, not clearance. I don't know which version of EN 60950-1 you're referring to, but in the 2006 version, Table 2L most certainly applies to clearances. I see nothing in 60950-1 that indicates values from table 2L are to be added to values from table 2K for clearances in secondary circuits. Maybe I missed something. Where were secondary circuits mentioned in the OP? Since Table 2K is for clearances in primary circuits and between primary and secondary circuits, and that all references were to mains voltages (as far as I could tell), I don't think clearances _in_ secondary circuits (which would invoke Table 2M) are involved in the question. Regards, Peter L. Tarver, PE ptar...@ieee.org CONFIDENTIALITY This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof. ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or any other person or entity. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email __
RE: Clause 2.10.3.3 of EN 60950-1:2006
From: Nick Williams Sent: Friday, June 29, 2007 5:21 AM Compare the two scenarios... 1. Say mains is 230V, i.e. below 300V so add clearances from Table 2K and 2L. Say peak working voltage is 840V. Clearance is 6.4+1.2=7.6mm From Table 2K, for a 840 Vpk working voltage across some bit of Reinforced Insulation, 6.4 mm is correct. For a 230V mains in Category II, Table 2J assumes a mains transient of 2,500 Vpk. For Pollution Degree 3, the additional Clearance from Table 2L is 1.2 mm. Your customer's interpretation appears correct. 2. Say mains is 400V, i.e above 300V so minimum CLEARANCES are determined from Table 2K. No mention of adding value from Table 2L. The mains transient voltage class is 4000V, which means that table 2K calls up larger clearances for voltages below 840V, but at 840V and above it makes no difference. Therefore clearance is 6.4mm. That's the way the standard reads. Can't be right, can it? It's Chiffon. (a regional advertisement reference.) This isn't an academic pursuit; we urgently need to know so thanks very much for any comments. Why this is the way it is, I really don't know, but must be based on TC 108's interpretation of IEC 60664-x, of which I have only an old copy. Your customer can pursue this through either reviewing IEC 60664-x or referring to Annex G of 60950-1. Regards, Peter L. Tarver, PE ptar...@ieee.org CONFIDENTIALITY This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof. ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina-SCI Corporation (or any of its subsidiaries), or any other person or entity. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email __
RE: Clause 2.10.3.3 of EN 60950-1:2006
Table 2L is for minimum creepage distances, not clearance. I see nothing in 60950-1 that indicates values from table 2L are to be added to values from table 2K for clearances in secondary circuits. Assuming (as 60950-1 does) that the overvoltage category of the product is II, then: Scenario 1 Mains voltage = 230V, giving a clearance of 5.0mm for reinforced (table 2K, based on 840V peak voltage) Scenario 2 Mains voltage = 400V, giving a clearance of 5.0mm for reinforced (table 2K, based on 840V peak voltage) It does seem counterintuitive that these numbers are the same, but that's the way the standard is written. It would also be the same number for a secondary circuit not subject to transient overvoltages! Maybe with a significantly boosted secondary voltage, transient effects reaching the secondary from mains are less significant than the value of working voltage itself? Something to consider - is the mains voltage of 400V in question 400V with reference to ground, or is this a 3 phase voltage? Also, one must keep in mind the minimum 10mm air gap required for reinforced between hazardous voltage and an accessible conductive part of the enclosure of floor-standing equipment, or of the non-vertical top surface of desk top equipment (should this apply). Scott Aldous Compliance Engineer Advanced Energy Tel: 970-407-6872 Fax: 970-407-5872 From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Steve Richardson Sent: Friday, June 29, 2007 7:58 AM To: emc-p...@ieee.org Subject: RE: Clause 2.10.3.3 of EN 60950-1:2006 Hi Nick, As I see it the clearance would be calculated as follows; Scenario 1 Mains voltage = 230V (mains transient voltage is 2500V) giving a clearance of 4.0 mm (table 2K) for reinforced, plus the additional clearance of table 2L for a PWV of 840V which would be 1.2 mm (ignoring extrapolation) giving a total of 5.2mm. Scenario 2 Mains voltage = 400V, then Table 2K gives a minimum distance of 6.4mm for reinforced with a PWV of 840V. Does anybody interperet this differently? Best regards, Steve Richardson Blackwood Compliance Laboratories From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Nick Williams Sent: 29 June 2007 13:21 To: emc-p...@ieee.org Subject: Clause 2.10.3.3 of EN 60950-1:2006 I've been asked the following question by a client: Compare the two scenarios... 1. Say mains is 230V, i.e. below 300V so add clearances from Table 2K and 2L. Say peak working voltage is 840V. Clearance is 6.4+1.2=7.6mm 2. Say mains is 400V, i.e above 300V so minimum CLEARANCES are determined from Table 2K. No mention of adding value from Table 2L. The mains transient voltage class is 4000V, which means that table 2K calls up larger clearances for voltages below 840V, but at 840V and above it makes no difference. Therefore clearance is 6.4mm. Can't be right, can it? This isn't an academic pursuit; we urgently need to know so thanks very much for any comments. Now, I'm not particularly familiar with this standard and the guy here who normally deals with this sort of thing is on holiday for three weeks, so I was hoping someone might be able to help out in the meanwhile. I think the key to this is in understanding the meaning of PEAK WORKING VOLTAGE and understanding its relationship with the AC MAINS SUPPLY. Could someone with some practical experience shed some light on this? Thanks and regards Nick. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries
RE: Clause 2.10.3.3 of EN 60950-1:2006
Hi Nick, As I see it the clearance would be calculated as follows; Scenario 1 Mains voltage = 230V (mains transient voltage is 2500V) giving a clearance of 4.0 mm (table 2K) for reinforced, plus the additional clearance of table 2L for a PWV of 840V which would be 1.2 mm (ignoring extrapolation) giving a total of 5.2mm. Scenario 2 Mains voltage = 400V, then Table 2K gives a minimum distance of 6.4mm for reinforced with a PWV of 840V. Does anybody interperet this differently? Best regards, Steve Richardson Blackwood Compliance Laboratories From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Nick Williams Sent: 29 June 2007 13:21 To: emc-p...@ieee.org Subject: Clause 2.10.3.3 of EN 60950-1:2006 I've been asked the following question by a client: Compare the two scenarios... 1. Say mains is 230V, i.e. below 300V so add clearances from Table 2K and 2L. Say peak working voltage is 840V. Clearance is 6.4+1.2=7.6mm 2. Say mains is 400V, i.e above 300V so minimum CLEARANCES are determined from Table 2K. No mention of adding value from Table 2L. The mains transient voltage class is 4000V, which means that table 2K calls up larger clearances for voltages below 840V, but at 840V and above it makes no difference. Therefore clearance is 6.4mm. Can't be right, can it? This isn't an academic pursuit; we urgently need to know so thanks very much for any comments. Now, I'm not particularly familiar with this standard and the guy here who normally deals with this sort of thing is on holiday for three weeks, so I was hoping someone might be able to help out in the meanwhile. I think the key to this is in understanding the meaning of PEAK WORKING VOLTAGE and understanding its relationship with the AC MAINS SUPPLY. Could someone with some practical experience shed some light on this? Thanks and regards Nick. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list.Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald:emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email __
