1. Home
  2. Electronics Design
  3. Paralleling L-C feed-thru filters for increased current capacity

Paralleling L-C feed-thru filters for increased current capacity

I'm currently working on a power supply which must meet the EMC requirements of def-stan 59-41 land class A. The power supply is housed in and aluminium enclosure with separate chambers for the various sections of the power supply. The initial design which I wasn't involved in uses multiple feed-thru filters connected in parallel when passing connections through the internal bulkheads, the currents involved are around 30A. My gut feeling is that this is a bad idea, partly because they my not share the DC currents evenly, but more of a concern is that connecting them in parallel will create high Q L-C resonant loops detrimentally effecting the EMI filtering.

Has anybody ever successfully paralleled feed-thru filters or should I just try to source larger feed-thru's capable of carrying the full currents involved?

Mark

Reply to
mark
Loading thread data ...

If they're all the same model and make they should have similar DC resistances -- you could check. The inductors will be made with metal wire, whose resistance increases with temperature; if one starts to get hot it'll tend to shed load onto the others.

Many near-identical L-C filters in parallel will make a filter that's a bit broader, but no more highly resonant than one. I think you're safe there.

If it's _really_ a concern, why not test for it?

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html
Reply to
Tim Wescott

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.