The 20m screened cable test is meant to test for the effects of a high surge current being carried on the shield between two, grounded EUT's.
The intent of the standard is to test products in a configuration in which they would be installed, so unless the detectors are installed with 20m of cable between each one, I'd argue that your test lab is nuts.... In order to perform the test for screened cables, the item at each end of the shielded cable needs to be grounded so that you can insert a surge generator in such a way as to cause a surge current to flow on the surface of the cable. Don't know enough about your product to comment of the practicality fo such a test..... Hope it's helpful... Mike Hopkins Thermo KeyTek -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: Thursday, October 31, 2002 10:48 AM To: [email protected] 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] 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"
