All, It seems that I could possibly pass the testing with a suppression device between Line and Chassis (probably from Neutral to chassis as well).
Some experiments with TVS diodes that I have on hand have been promising. However, the diodes can't stand up to the multiple surges. i.e. I get passing test results until the TVS diodes are reduced to a broken pile piece of Silicon with all of its smoke let out. I'm also concerned with leakage current. My design already has a MOV from Line to Neutral; but I have heard that such components are taboo from Line to Chassis or Neutral to Chassis. Is there a "Y rated" TVS, MOV, Sidactor... out there? I'm tempted to try some 4700pF Y caps that I have around to see if they'll soak up the surge a little bit. Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | > -----Original Message----- > From: Chris Maxwell > Sent: Friday, May 02, 2003 8:33 AM > To: 'EMC-PSTC Internet Forum' > Subject: Vicor Power Supply Surge Immunity > > Colleagues, > > Has anyone out there designed power supplies based on the Vicor 2nd generation converters? I have a design based on the Vicor "FARM" (Filter And Rectification Module) with two Vicor V300 series DC-DC converters behind it. > > I can't get this design through surge testing at 500V/250V, even though the data sheets for all of the modules claim immunity to 2KV/1KV. I'm not taking issue with the data sheets, Vicor makes good stuff. I just can't figure out what's up with this design. > > I have followed the spec sheet protection recommendations to the letter. I have suspected the Corcom 6ED8 filter in front could be causing "ringing" of the surge; but found that the failure occurs with or without the filter. > > The failure is very strange in that it: > -Is load dependent. It seems that a higher load makes failure more likely > -It happens at a random time, up to 17seconds after the surge. > -Is characterized by the FARM's enable signal (which controls the V300s behind it) going low. > -I can get some improvment (pass 500/250 but fail 1000/500) if I remove chassis ground from the FARM heatsink. > > It almost seems as though the surge is passing through the FARM to its grounded heatsink, along the way, maybe it is heating up some components, perhaps this heat takes a little while to get to the FARM's thermal shutdown circuit, which then dumps the enable signal (I know, really far fetched.) > > Maybe a layout problem? > > I'd appreciate any experience that others could share with this. > > Thanks, > > Chris Maxwell | Design Engineer - Optical Division > email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 > > NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA > web www.nettest.com | tel +1 315 797 4449 | > > > > 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 Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
