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Someone asked before how to get parameters for ferrite bead simulation.

The same method doesn't really work for clamps because almost all of them don't give information about resistance.

I began looking for available spice models and Wurth for example has a host of bead models you can download but none for clamps. I don't think they are being lazy so maybe there is a reason? Like not using the same simulation method as a ferrite bead.

So how do you do it for a clamp and how to get the parameters?

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  • \$\begingroup\$ Anywhere you have an impedance curve, you can fit an RLC network to it. Is that what you want to know, then? Note that, if you want a full cable-level model, you'll have to work at it, modeling each wire and their mutual couplings (L, C or TL); such a model can be rather nontrivial, which also might explain the lack of extant models for such components. \$\endgroup\$
    – Tim Williams
    Commented Feb 16 at 8:01
  • \$\begingroup\$ Okay there is an L with Rp, Cp and preceded by Rs model for ferrite beads, do you mean that I can fit the impedance curve of the ferrite clamp to this? I would like to know that yes. A link would probably be fine. I have both an AC and DC system on a boat. The AC system seems to be blowing a 4A fuse on a device in the DC network. In order to prevent any injection from the AC into DC I am trying to add a ferrite clamp to wiring harness of DC device. I want to predict if adding a ferrite clamp on the device power input will cause oscillations due to resonance at different load conditions. \$\endgroup\$
    – Tony
    Commented Feb 16 at 8:15
  • \$\begingroup\$ That sounds like a wildly different system to which ferrites are applicable. If you mean AC as in mains say 50-400Hz, ferrite impedance is almost nothing down there, even for industrial-size ones. Such models are most useful in the 1-100MHz range where cable EMI can be simulated, potentially without too much difficulty, or as a part of full-field EMI simulations. \$\endgroup\$
    – Tim Williams
    Commented Feb 16 at 8:39
  • \$\begingroup\$ I think the clamp-on bead model is the same as the integrated bead model. The series resistance should just be the DC resistance of the wire that goes through the ferrite structure. If it’s just a single loop then it’s probably negligible. The reason integrated beads have higher DC resistance is that they have a large internal coil structure exposed to the ferrite material. \$\endgroup\$
    – Ste Kulov
    Commented Feb 19 at 6:44

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