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Eric, Can you put a slot in the board between the pins of the components with inadequate creepage? If so, then the creepage distance from one pin to the other would include the distance to go around the slot; which may solve part of your problem. Chris Maxwell Nettest Utica, NY 315-266-5128 From: [email protected] mailto:[email protected]] On Behalf Of Meunier, Eric Sent: Thursday, May 27, 2004 8:51 PM To: '[email protected]' Subject: 60VDC Telecom Power Creepage http://www.ieee-pses.org/symposium http://www.emc2004.org/ Hi, I am looking for guidelines to design a 36-75VDC input DC/DC converter powered from Secondary TNV2 Telecom Power with regards to the applicability of creepage requirements of IEC60950 table 2L to Functional insulation and potential damage to Basic insulation from overload conditions. I found that many components rated at 100VDC do not allow for the 1.4mm creepage specified in table 2L for the PCB land patterns and component body. Also, low voltage control circuits have much less than the 1.2mm creepage specified for 50VDC and below. Based on section 5.3.4 c), it seems that these spacing requirements can be waived where there is no risk of fire or damage to nearby Basic insulation. The PCB on which the components will be mounted is FR-4 rated V0. We have fusing that will protect the larger traces of the circuit if a short circuit test is done such as in 5.3.4 c) but is this effective in real life where leakage current due to creepage would gradually increase and damage the isulation rather than the trace? What kind of risk does smaller traces not properly fused represent for the short-circuit test and in real life? If the PCB provides solid Basic insulation between an external layer power trace and an internal layer ground plane, should I consider there is a risk of damage to the solid Basic insulation if the Functional insulation between the Power trace and other external Power traces does not meet table 2L requirements or is not properly fused? Thanks, Eric =================================== Éric Meunier Designer EMC/Environmental E-mail: [email protected] Kontron Canada Inc. 616, rue Curé-Boivin Boisbriand, Québec Canada, J7G 2A7 Tel: 1-450-437-4661 ext. 2419 Fax: 1-450-437-8053 This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. IEEE PSES Main Website: http://www.ieee-pses.org/ To post a message send your e-mail to [email protected] Instructions for use of the list server: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] 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. IEEE PSES Main Website: http://www.ieee-pses.org/ To post a message send your e-mail to [email protected] Instructions for use of the list server: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
