David, This is going back a few years, and I'm no longer in telecom, but here's my memory...(BTW, the company no longer exists, so I feel I can talk about this)
I know Deutsche Telekom had CO's with the higher voltages - maybe BT also but I don't think so. During charge cycles, the voltage would be around 72Vdc so TNV-2 was necessary. However, going through the work wasn't that much extra cost (it shouldn't have been that much - DC-DC converters were rated for TNV-2 and we used opto-isolators, but I think these were part of my product's design anyway). Spacings was the biggest headache but this was just a one time labor cost and didn't take that much time once I identified the boundary of the TNV-2 circuits. So, I guess the answers to the questions are more questions: a) do you already use TNV-2 rated (or higher) DC-DC supplies/inverters within your product? b) if opto-isolators are already used, what are they rated to? c) do you have another board spin coming where you can correct any spacings less than 39 or 40 mil (whichever it is - memory is fuzzy there) d) do you have any other circuit interfaces that would bridge the TNV-2 to SELV circuits? And: are you targeting DT or other EU carriers who may have this higher voltage requirement as part of their default RFQ? It could well be that only one-time charges would be involved, and if these are happening anyway (i.e. board spin), why not increase the spacings while you're at it and achieve the basic insulation spacings for "free"? Well, that was fun, now back to my current work... -Dave David Heald EMC Engineer | Worldwide Regulatory Compliance tel: +1.631.738.5373 fax: +1.631.738.5520 From: [email protected] [mailto:[email protected]] On Behalf Of David Gelfand Sent: Thursday, August 31, 2006 4:43 PM To: [email protected] Subject: -48Vdc powered equipment Hello group, My question is more market-oriented than technical. A friend is designing a -48Vdc powered voice over data product intended to be CE marked, and sold in Europe and Africa. The debate has come up whether to design the input as SELV or TNV-2. I understand that in Europe, battery voltages can exceed 60Vdc, in which case the input is considered TNV-2 and basic insulation is assured between input and SELV circuits. However this will be customer premise equipment, not for network operators. Are there other situations where battery voltages could exceed 60Vdc apart from telco operators? His real questions are, Is it worth the extra expense to design in basic insulation? If he declares the input as SELV only will he lose potential customers? Thanks in advance, David David Gelfand Product Integrity Mitec Telecom Inc 9000 Trans-Canada Highway Pointe-Claire, QC Canada H9R 5Z8 514 694 9000 x2262 - 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 [email protected] 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 [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ________________________________________________________________________ This email has been scanned for computer viruses. ________________________________________________________________________ This email has been scanned for computer viruses. - 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 [email protected] 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 [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] 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 ______________________________________________________________________
