How to understand this formula.?

I am having ferrite core T60006-L2063-W517 Ferrite Toroids /Ferrite Rings Core 63x50x25 58.6uH@10kHz. I wanted to measure inductance of the core from datasheet it shows,

Ferrite Rings Core 63x50x25 58.6uH@10kHz what does this mean by the way..? Inductance test without DC-magnetisation :

Setting values: Ieff x N = 40 mA f = 10 kHz

Specified value: 44 µH ≤ AL ≤ 85 µH

but doesn't ring a bell can anyone suggest me on this please...?

Datasheet of T60006-L2063-W517

• I believe I disagree with the formulas suggested in the two answers I see. Sometimes, the AL value tells you the inductance you get with 100 turns, not 1. (The inductance is proportional to $N^2$.) Your value seems too high, taking into account the magnetic path length and all the common materials from rather low to rather high $\mu_r$ values. So I think in this case the AL value is specified per 100 turns. Not 1 turn. But I may be wrong, too, as I'm just guessing. My recommendation to you is to not assume. Wire up 100 turns exactly and measure. See what you get. Let us know.
– jonk
Apr 12, 2021 at 18:01

Ferrite Rings Core 63x50x25 58.6uH@10kHz what does this mean by the way..?

Well, that information is directly from the mouser website and, it is at odds with the data sheet. The Mouser website is appearing to say this: -

• Outer diameter = 63 mm (data sheet states 67.3 mm)
• Inner diameter = 50 mm (data sheet states 46.5 mm)
• Width = 25 mm (data sheet states 28.6 mm)
• Inductance 58.6 μH (data sheet states 59 μH)

So, it's unclear where Mouser pulled this information from. However, further down the Mouser page they do state things that match the data sheet. So, my advice is ignore that earlier statement and stick with what the data sheet tells you.

Specified value: 44 µH ≤ AL ≤ 85 µH

That information is telling you what the range of values the inductance may be for one turn of wire. In other words it's their guarantee that if you bought a hundred units and tested each unit you might get a range of inductance that approached those limits.

Setting values: Ieff x N = 40 mA f = 10 kHz

Here, they are telling you how the test can be done. They talk about Ieff and N and the product of those must be equal to or less than 40 mA. In normal-speak, they are saying that there is a limit on the ampere-turns used when measuring inductance. They say this because it's quite tricky to measure inductance with just one turn and you may choose to wind (say) ten turns. If you wind ten turns then make sure your test current is less than 4 mA and, in all probability that is the peak current of the 10 kHz sinewave you apply. The ampere-turn limit is to avoid transformer core saturation giving an inductance value that is falsely low.

Bear also in mind that 10 turns will produce a nominal inductance value of 100 x 59 μH because inductance is proportional to turns squared.

The inductance depends on the material and the geometry of the magnetic core as well as the number of turns of the coil. The $$\A_L\$$ value is basically an inductance for a one-turn coil used with the given magnetic core. This simplifies the calculation of the inductance of a coil to: $$L = A_L N^2$$

with $$\N\$$ being the number of turns. There is usually a rather large tolerance on $$\A_L\$$, but it is an easy starting point when selecting magnetic cores.