laminated iron core DC high current filter choke vs. CT toroid

[MikeHS]

Is it feasible to press a surplus current transformer (toroid type) into acceptable service as a DC power choke for 100 & 120 HZ
ripple? I calculated a needed L of about 1.8 to 2milliH of L. Any one had success doing something similar?
Thanks,
MikeHS

 

[ScottyUK]

If you have a DC component then you will likely have saturation problems if you use an AC core unless you can introduce an airgap.


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If we learn from our mistakes I'm getting a great education!

 

[OperaHouse]

about 1.8 to 2milliH of L

That seems rather low value. Not a very critical application. I've used low voltage transformer secondaries.

 

[electricuwe]

I agree to Scotty UK. But you should keep in mind that the main difference between a transformer and a choke is the airgap

- transformer --> no energy storage --> high µ material, no airgap
- choke --> energy storage --> airgap (or distributed airgap by using low µ material)

 

[Comcokid]

A current transformer (CT) will not make a good filter inductor. Most CT are designed using a core with moderately high permeability (u value). If the CT was intended for a frequency response to a few 10's of kHz, then the core is likely a ferrite - a very poor choice for low frequency where all the current is essentially magnetizing current, that is: low frequency AC current is equivalent to having a DC bias current and it takes very little to saturate a high u core.

Now, the core of a CT would be a good choice as a common mode choke, but the single high-turn winding of a CT is not suitable as the winding of a common mode choke.