Hi Nevin, George, and the group, Although "screened" ethernet systems are favored in Europe, some of them perform considerably worst than unshielded systems in terms of emissions and immunity. Some poorly designed systems (use of pigtails on shields) radiate more, and even the best systems cannot match the immunity performance of unshielded systems in tests I helped perform in Switzerland a few years ago. The paper, published at Roma94 is posted on my site at:
http://emcesd.com/pdf/roma94.pdf It is interesting to note that even good shielded systems can induce failures of PCs in IEC 61000-4-4 by providing a low impedance path for the common mode EMI to get "into the works" of the PCs, quite separate issue from the data transmission itself. Unshielded systems do not do this because of the CM chokes and balancing transformer design in the interface circuity. Doug neve...@attbi.com wrote: > To my knowledge, only when the Class B for Central-Office equipment has to be > met. > > Neven > >>Hello Group, >> >>I heard recently that shielded Ethernet cables have become something of >>a customer-expectation-based defacto standard in Germany for >>installation of network type ITE equipment (routers, switches, >>firewalls, etc.) Can anyone confirm or comment on that. Is it like >>that anywhere else? >> >>Thanks >> >>George Stults >>WatchGuard Technologies Inc. >> -- ___ _ Doug Smith \ / ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----( ) | o | Email: d...@dsmith.org \ _ / ] \ _ / Website: http://www.dsmith.org This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
