Dude, The CO will wire your power inputs with two separate power pairs feeding from two different sources. This way, if there is some fault in the 'primary' centralized distributed DC source, the redundant source can take over without the product losing power.
I think the test method depends on how your product chooses which feed to draw from. If your product diode-OR's the inputs, only the feed with the higher voltage will actually power the entire product. If this is the case, I would recommend using two supplies and differing the voltages on your supplies so that one supply is a few volts higher than the other. Take your readings on both the higher voltage (loaded) feed as well as the lower voltage (unloaded) feed. Just be certain to recheck your voltages at the input to your product to make sure that there is still a few volts of difference between the feeds after the inductors are placed in front of the loaded LISNs (assuming this is the test you're doing). OK, now that I think about it - this method should work well for just about any redundant power scheme. Quiet DC supplies are also enormously important if filters are not present on the output of the secondary DC source. You don't need a lot of ampacity on the secondary supply if you set up the voltages correctly. (CS linears run at 52± when unloaded!!!!) Dave -----Original Message----- From: Plante, Dereck Raymond (Dereck) [mailto:drpla...@lucent.com] Sent: Tuesday, September 24, 2002 1:23 PM To: emc-p...@majordomo.ieee.org Subject: Central Office Wiring - Conducted Emissions Does a CO wire up to a redundant cabinet with 2 wires, so jumpered at the cabinet, or 4 wires (any theory on percentages)??? And if it is 4 wires, do the two Feeds go to two completely seperate sources, or are they jumpered sources (so in parallel)? How do people typically test there cabinet for Conducted Emissions??? We were testing with the cabinet jumpered and going throught the LISNs to one Source. We had a passing system with mods, and so we tried to only connect the LISN to one feed and power the other feed with a seperate DC source, then we got failing results with or without mods. Interesting..... We are thinking we are getting some crazy current loops. Does anyone have an opinion as to their best recommended test setup for conducted emissions that will best represent the true wiring in a central office? We are thinking, but have not yet tried, to test 4 wires coming out of the cabinet, going through 4 different LISNs and then going to one DC power source. Any comments??? Dereck R. Plante Compliance Engineer Lucent Technologies Switching Solutions Group, OPENet Solutions 255 Independence Drive Hyannis, MA 02601-1854 (508) 862-3302 ------------------------------------------- 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"
