Dear list members, I'm writing the EMC test spec. for a wayside railway equipment, reference standard is EN50121-4. I've got an interpretation problem on the surge test on I/O shielded cables: it's a balanced RS-485 like communication line, the shield is connected only at the EUT side. Cable lenght may sometimes exceed 30m.
EN50121-4 Table 3 (note 3) recommends a generator source impedence of 42 Ohm, both for line-to-line and line-to-gnd test and with no specific reference to shielded lines. But if I look at the test setup according IEC 61000-4-5 par. 7.6 (fig. 17), it requires a generator source impedence of 2 Ohm. Am I right supposing that the specific EN50121-4 standard has anyway priority over the 61000-4-5 and I have to use 42 Ohm ? Moreover, previous version of IEC 61000-4-5 suggested (in the above quoted fig.17) to add a 10nF termination capacitor between shield open end and gnd to simulate cable capacitance, why has it been removed ? Thanks in advance for your precious time Best Regards Francesco Campedelli Product Engineering - HW Design ALSTOM Ferroviaria s.p.a. E-mail: [email protected] :.________________ CONFIDENZIALE: Questo messaggio e gli eventuali allegati sono confidenziali e riservati. Se vi è stato recapitato per errore e non siete fra i destinatari elencati, siete pregati di darne immediatamente avviso al mittente. Le informazioni contenute non devono essere mostrate ad altri, né utilizzate, memorizzate o copiate in qualsiasi forma. CONFIDENTIALITY : This e-mail and any attachments are confidential and may be privileged. If you are not a named recipient, please notify the sender immediately and do not disclose the contents to another person, use it for any purpose or store or copy the information in any medium. - ---------------------------------------------------------------- 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
