In message <49c3718e3f1c9341a9fb7b5d1f05ceed01aa8...@de08ev806.global.ds.honeywell.c om>, dated Wed, 7 Jan 2009, "Sterner, David (NY80)" <[email protected]> writes:
>The immunity document for security systems, EN 50130-4, specifies a CDN >for screened cable; we use the Fischer CDN on video cable. EN 55024 >(ITE) does not specify a test procedure for screened cable. Our >comparative results on the same 75-ohm cable link indicate that the >CDN-75 provides a much more severe stress than the (Fischer) E-M clamp. If EN 61326-2-3 does not call for a CDN, in principle you do not need to look at other standards **and use a provision of such a standard outside its scope**. If a customer thinks that a CDN should be used, they should take that up with their national standards committee, proposing an amendment to the standard. > >Outlook: >Products that 'pass' using the E-M clamp on sccreened cables are very >likely to fail if retested, i.e. by an agency or an OEM customer. E-M >results on video products are likely to give one a false sense of >security; image degradation will be more severe with the CDN. Presumably those results apply to an unbalanced (coaxial) interconnection. With a two-wire connection, if it is balanced, it may be very difficult indeed, perhaps impossible, to obtain or build a CDN that does not degrade the balance and thereby give a very pessimistic result. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Things can always get better. But that's not the only option. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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]>
