On 1/26/2006, Peter Tarver wrote:
However, I have a product design engineer claiming earthing of one of the conductors at the output of the bulk ring generator is typical. Earth referencing, in my experience, typically occurs near the individual T/R interfaces, just before ring trip circuitry. Hi Peter: I don't think earthed ringing with no DC bias is typical in North America, but I believe it is typical in some other countries such as the UK. In the UK, the typical configuration applies a ground referenced AC ring signal to the B lead, and a ground referenced -48 VDC to the A lead. Even in North America, though, the composite AC+DC ring signal that appears on the bulk ringing bus (and under ringing conditions, on the ring lead) is ground referenced. The only ground that is applied at the line card is to ground the tip lead to complete the circuit while ringing is being applied to the line. So, in a sense, both configurations involve a "grounded referenced" bulk ringing source, but in North America there is a DC bias while in the UK there is not. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) [email protected] http://www.randolph-telecom.com <http://www.randolph-telecom.com/> - ---------------------------------------------------------------- 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
