Re: [PSES] IEC 61010-1 Table K.17
Rich, I can see your point. As a result of rapid polarity reversals, the acceleration of an ion across the mean free path of a gas will be halted and even reversed. I will read this paper to gain a better understanding but at this time I believe this will only affect gas breakdown as a result of impact ionization. Thanks for the link, Doug On Tue, Aug 11, 2015 at 5:08 PM, Richard Nute ri...@ieee.org wrote: Hi Doug: A simple (and therefore incomplete) explanation: Breakdown in air requires the ions to travel from one pole to the other before the polarity reverses. At high frequencies, the polarity reverses before the ions can travel the distance between the poles. At high frequencies (compared to mains frequencies) the clearance can be less. See: http://lss.fnal.gov/archive/other/ssc/sscl-539.pdf http://ewh.ieee.org/r10/taiwan/pses/archive/2012_04_27/IEEE%20PSES%20April/TC108%20hf_FC_v.1.2_IEEE%20PSES%20TAI.pdf Best regards, Rich -- Original Message -- From: Doug Powell doug...@gmail.com To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] IEC 61010-1 Table K.17 Date: Fri, 7 Aug 2015 16:47:28 -0600 All, I am evaluating spacings for an RF product that operates at 13.56 MHz and can produce maximum voltages of 5,000 Vrms (7,070 Vpk). If I do an interpolation of using Table 6 (Mains 230 V, OV Cat II, indexing on 5,000 Vrms), I get a minimum clearance requirement of 14.9 mm. When I do the same calculation on Table K.17 (column 3, indexing on 7,070 Vpk), I get 12.7 mm. Now I understand the effects of high frequency voltage stress causing air molecules to become more energetic and therefore more likely to break down at lower voltages. So why in this case does IEC 61010-1 Table K.17 result in lower clearance values than Table 6? Somehow, this just seems wrong. *Please note that in the case of high frequencies paragraph K.3.1 indicates I am to skip over section K.3.2 with the D1 + F × (D2 – D1) calculations.* Thanks a bunch! Doug Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 -- Douglas E Powell doug...@gmail.com Skype: doug.powell52 http://www.linkedin.com/in/dougp01 - 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://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas sdoug...@ieee.org Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] IEC 61010-1 Table K.17
Doug, The standard must assume the RF circuits are even more energy-limited than secondary circuits is my best guess. If so, it doesn't say that anywhere I could find. It takes voltage, but also energy to create an ionizing path. Regards, Brian Gregory 720-450-4933 -- Original Message -- From: Doug Powell doug...@gmail.com To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] IEC 61010-1 Table K.17 Date: Fri, 7 Aug 2015 16:47:28 -0600 All, I am evaluating spacings for an RF product that operates at 13.56 MHz and can produce maximum voltages of 5,000 Vrms (7,070 Vpk). If I do an interpolation of using Table 6 (Mains 230 V, OV Cat II, indexing on 5,000 Vrms), I get a minimum clearance requirement of 14.9 mm. When I do the same calculation on Table K.17 (column 3, indexing on 7,070 Vpk), I get 12.7 mm. Now I understand the effects of high frequency voltage stress causing air molecules to become more energetic and therefore more likely to break down at lower voltages. So why in this case does IEC 61010-1 Table K.17 result in lower clearance values than Table 6? Somehow, this just seems wrong. Please note that in the case of high frequencies paragraph K.3.1 indicates I am to skip over section K.3.2 with the D1 + F × (D2 ndash; D1) calculations. Thanks a bunch! Doug Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 - 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://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas sdoug...@ieee.org 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://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas sdoug...@ieee.org Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] IEC 61010-1 Table K.17
Hi Doug: A simple (and therefore incomplete) explanation: Breakdown in air requires the ions to travel from one pole to the other before the polarity reverses. At high frequencies, the polarity reverses before the ions can travel the distance between the poles. At high frequencies (compared to mains frequencies) the clearance can be less. See: http://lss.fnal.gov/archive/other/ssc/sscl-539.pdf http://ewh.ieee.org/r10/taiwan/pses/archive/2012_0 4_27/IEEE%20PSES%20April/TC108%20hf_FC_v.1.2_IEEE% 20PSES%20TAI.pdf Best regards, Rich -- Original Message -- From: Doug Powell doug...@gmail.com mailto:doug...@gmail.com To: EMC-PSTC@LISTSERV.IEEE.ORG mailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] IEC 61010-1 Table K.17 Date: Fri, 7 Aug 2015 16:47:28 -0600 All, I am evaluating spacings for an RF product that operates at 13.56 MHz and can produce maximum voltages of 5,000 Vrms (7,070 Vpk). If I do an interpolation of using Table 6 (Mains 230 V, OV Cat II, indexing on 5,000 Vrms), I get a minimum clearance requirement of 14.9 mm. When I do the same calculation on Table K.17 (column 3, indexing on 7,070 Vpk), I get 12.7 mm. Now I understand the effects of high frequency voltage stress causing air molecules to become more energetic and therefore more likely to break down at lower voltages. So why in this case does IEC 61010-1 Table K.17 result in lower clearance values than Table 6? Somehow, this just seems wrong. Please note that in the case of high frequencies paragraph K.3.1 indicates I am to skip over section K.3.2 with the D1 + F × (D2 D1) calculations. Thanks a bunch! Doug Douglas E Powell doug...@gmail.com mailto:doug...@gmail.com http://www.linkedin.com/in/dougp01 - 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://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas sdoug...@ieee.org Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
[PSES] IEC 61010-1 Table K.17
All, I am evaluating spacings for an RF product that operates at 13.56 MHz and can produce maximum voltages of 5,000 Vrms (7,070 Vpk). If I do an interpolation of using Table 6 (Mains 230 V, OV Cat II, indexing on 5,000 Vrms), I get a minimum clearance requirement of 14.9 mm. When I do the same calculation on Table K.17 (column 3, indexing on 7,070 Vpk), I get 12.7 mm. Now I understand the effects of high frequency voltage stress causing air molecules to become more energetic and therefore more likely to break down at lower voltages. So why in this case does IEC 61010-1 Table K.17 result in lower clearance values than Table 6? Somehow, this just seems wrong. /Please note that in the case of high frequencies paragraph K.3.1 indicates I am to skip over section K.3.2 with the D1 + F × (D2 – D1) calculations./ Thanks a bunch! Doug Douglas E Powell doug...@gmail.com http://www.linkedin.com/in/dougp01 - 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://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas sdoug...@ieee.org Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
