On Fri, 8 Mar 2013 14:10:02 +0000, John Woodgate <[email protected]> wrote:
>>Please give me your experts comments. > > 7.2 of IEC/EN 61000-4-5 says (among other things): > > If there are no other possible connections to earth, line-to-ground > tests may be omitted. I think maybe the paragraph can cause some confusion. For example, a Class II power supply unit may be intended to be used with small PC peripherals which itself doesn't have connections to earth and the manufacturer may assume that the unit have no connection to earth. But in real application, maybe the peripheral be connected to a Class I desktop PC, and in that situation, the 0V output terminal of the power supply unit may be actually connected to the earth. In this case, the unit may have "possible connections to earth". In the situation the unit really doesn't have any possible connection to earth, maybe we can expect that the the unit must not sensitive to line-to-ground surge (actually, where the surge stress applied?) and may omit line-to-ground surge test as described in the standard. However, if we knew that the unit actually sensitive to line-to-ground surge, is it really wise to use the unit as is? Regards, Tom -- Tomonori Sato <[email protected]> URL: http://homepage3.nifty.com/tsato/ - ---------------------------------------------------------------- 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 <[email protected]> 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://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]>
