Just create a pair of large air coils wit suitable diameter and calculate the appropriate decoupling caps for the switching frequency. Repeat the network if necessary.
You might need to connect the sense wires to the output of the network. Keep distance to the air coils with wiring and EUT and/or respect the 90 degree Angle rule between wiring and coils. You will be surprised how large the inductance becomes when you are using 20" diameter of coils. Gert Van: [email protected] [mailto:[email protected]] Namens Derek Walton Verzonden: vrijdag 21 augustus 2009 19:00 Aan: Ken Javor CC: [email protected] Onderwerp: Re: 28 volt Linear Power Supply Hi Everyone, thanks for the constructive comments so far. I'm not really in a position to use batteries, my voltage spec is very tight at +- 0.5 volts. I have tried running through the facility filters, they are 100 amp rated, but I think a combination of that impedance and the LISN impedance is too much for the EUT starting current. It seems I can start the EUT with just the LISN's, but then I have too much noise from my power source. I swapped the room filters for some 10 uF caps, same ones that are called out in MIL std testing, and I almost get quiet enough. Ideally, I'd like to find a quieter source rather than try to filter..... Sincerely, Derek Walton Ken Javor wrote: > That would be on the power input. Derek is looking at cleaning up the > output. For his load, the LISNs will dominate the input impedance above > about 10 kHz. If those batteries are in place in the test chamber the > facility filters have been completely bypassed. > > Ken Javor > > Phone: (256) 650-5261 > > > >> From: Ralph McDiarmid <[email protected]> >> Date: Fri, 21 Aug 2009 09:35:54 -0700 >> To: <[email protected]> >> Conversation: 28 volt Linear Power Supply >> Subject: RE: 28 volt Linear Power Supply >> >> I've seen facility filters make some power supplies oscillate too. >> >> >> Ralph McDiarmid, AScT >> Compliance Engineering Group >> Xantrex Technology Inc >> >> >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] On Behalf Of Ken >> Javor >> Sent: Friday, August 21, 2009 9:12 AM >> To: [email protected] >> Subject: Re: 28 volt Linear Power Supply >> >> Your facility EMI filters should provide 100 dB of insertion loss >> (MIL-STD-220, 50 Ohm system). >> >> If that isn't enough, you can bypass the 28 Volt output with a couple >> lead >> acid car batteries. Then you can use a pair of 10 uF feedthrough caps >> you >> have laying around, and finally your LISNs. >> >> If all that doesn't do the job, you need to do some troubleshooting, see >> if >> some of the noise isn't common mode (not spec'd by manufacturer) and >> build >> your own cm choke. >> >> Ken Javor >> >> Phone: (256) 650-5261 >> >> >> >>> From: Derek Walton <[email protected]> >>> Date: Fri, 21 Aug 2009 10:13:33 -0500 >>> To: "[email protected]" <[email protected]> >>> Subject: 28 volt Linear Power Supply >>> >>> Good morning folks, >>> >>> I have been requested to perform a conducted emissions test on a unit >>> that draws up to 50 amps from a 28 volt source. >>> >>> I have a 300 amp supply and its a little too noisy being a switcher. >>> >>> Can anyone suggest a make/model that can do 28 volts at up to 50 amps >>> thats either linear or super quiet please. Its very hard researching >>> >> how >> >>> quiet supplies are. >>> >>> Many thanks, >>> >>> Derek Walton >>> L F Research >>> >>> - >>> ---------------------------------------------------------------- >>> 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]> >>> >> - >> ---------------------------------------------------------------- >> 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]> >> >> - >> ---------------------------------------------------------------- >> 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]> >> > > - > ---------------------------------------------------------------- > 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]> > > - 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]> - 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]>
