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I want to use Gaia EMI filter. my load requirement is 1.7 A continuous and 3.5A Max. Voltage is 28 V. Because of the max current I have to use FGDS-10A-50V(load current can go up to 10A) but this size to too much for me. So my question is if I use FGDS-2A-50V(load current 2A) filter and when in some case my current will go 3.5 A what will happen with the filter? will it stop working and when my load will be again less the 2 A it will start filtering..? Or once the current will go high my 2 A filter will not be workable again.

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    \$\begingroup\$ It is likely to release the magic smoke. \$\endgroup\$
    – Peter Smith
    Jul 25, 2018 at 11:31
  • \$\begingroup\$ @PeterSmith can You provide any proof for that? It will be helpful. \$\endgroup\$
    – Dinesh Dangi
    Jul 25, 2018 at 11:35
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    \$\begingroup\$ I can only state that I have seen it happen. The datasheet may be informative; otherwise, contact the manufacturer. \$\endgroup\$
    – Peter Smith
    Jul 25, 2018 at 12:05
  • \$\begingroup\$ If you don't like to respect the parts specifications, you should use another part. \$\endgroup\$
    – Uwe
    Jul 25, 2018 at 14:35

2 Answers 2

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The current limit is based mainly on the inductors used inside the filter. If you exceed the peak current rating, two things can happen:

  1. The inductor saturates, reducing its value significantly. This reduces the effectiveness of the filter, allowing a burst of EMI out of (or into) your product. Obviously, this is something you care about, or you wouldn't be using the filter in the first place.

  2. The inductor overheats, potentially damaging it permanently, or at least reducing its useful lifetime. Again, something you no doubt want to avoid.

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Inductance can saturate and drop sharply above the -10% threshold used for DC rating.

Heat rise depends on DC or RMS Amps squared times resistance loss in filter.

Thus 5 times rated current means 25x temperature rise in the inductor above ambient.

Do not exceed the rating unless you know the consequence.

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    \$\begingroup\$ And even if thermally it is viable... The saturation of the magnetics will change the filter response THUS its rejection capability isn't the same \$\endgroup\$
    – user16222
    Jul 25, 2018 at 12:12

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