Seeking square law torroid core

[Flyback]

Hi,
We are seeking a "square law" ferrite torroid to use as a fluxgate sensor for imbalance current detection. For 50Hz mains electricity.
No manufacturer seems to make these.
I tried Far-rite, Mag-inc, Ferroxcube and TDK, but no joy. Plenty of high permeability (eg 5000), but no "square law".
We need OD= >35mm, ID = >15mm
Please Do you know of any?

 

[ronsimpson]

Hi Flyback,

Many years ago I did some work for PNI studying the earth's magnetic fields. They used a square flux core. I don't find then in my junk core pile. I will look more.
I also have some "mag amps" from coilcraft. No longer being make. I do have some power cores built to sharply saturate. magnetic amplifier: coilcraft has removed all information they had.

Not much help.

 

[Flyback]

Thanks, is "nanocrystalline" possibly a "square law" core (some versions of it)? I believe ferrite cant be square law?

 

[ronsimpson]

What I have has a sharp saturation point. It is designed to go from high inductance to very low fast.
Try this
ebay
Tape Wound?

 

[Buk]

Not sure that they consistute "square law", but amorphous iron (metallic glass) cores have much lower coercitivity and higher permeability than most (all?) other materials.

Try these guys: https://mhw-intl.com/amorphous-and-nickel-iron-cores/
Or these:https://www.hilltech.com/products/power_components/amorphous_nanocrystalline_cores.html