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 ______________________________________________________________________
