This is a good example of an inarticulate clause in a standard. One sentence in clause 7.5 reads "Normally, the maximum length of the specified shielded cable shall be used. But the following sentence reads "With respect to the frequency spectrum of the surge 20 m length of the specified shielded cable shall be used in non-inductively bundled configuration for physical reasons." Duh! What they heck are they trying to say in that last sentence? Are we expected to use the maximum length cable specified for the application but no longer than 20 m? That's seems to be what is being said in a convoluted way.
Richard Woods Sensormatic Electronics Tyco International -----Original Message----- From: am...@westin-emission.no [mailto:am...@westin-emission.no] Sent: Thursday, October 31, 2002 10:48 AM To: emc-p...@majordomo.ieee.org Subject: Surge - injection point on screened cable According to IEC/EN 61000-4-5, the surge pulse shall be injected onto a screened cable 20 meters from the DUT. We have a fire alarm system with 20 detectors connected on the same screened cable, 1.5 meters between each detector. We have been told from the local test lab that we have to add a 20m cable between each detector in order to surge test each detector. I'm sure our local cable distributor like that idea ... , but do we really have to do this ? Why is this 20 meters cable needed ? Is it to induce the surge pulse from the screen into the cable lines? The 20 detectors make a total cable distance of 30 meters and the screen is continuous. Is it possible to insert a pulse in the beginning of the cable and test all detectors simultaneous ? Regards Amund ------------------------------------------- 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 All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- 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 All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
