Is this inductor dubious?

Thread Starter

Ian0

Joined Aug 7, 2020
5,504
https://www.rapidonline.com/white-label-534455-toroidal-chokes-inductivity-1-mh-250-vac-16-a-50-1210
The inductor claims to be rated at 1mH @ 16A DC.
The core is iron powder od=26mm, id=14.5mm, h=20mm with a relative permeability of 6000, and the winding is 10 turns.
From this I calculate a cross sectional area of 115mm^2 and a magnetic path length of 63mm.
I've never seen iron powder with μ greater than about 180, so I wonder if it really is ferrite.
10 turns at 16A is a magnetomotive force of 160A. Permeance (Al) is 10μH/t^2, reluctance is 100000
That gives a flux of 1.6mWb and a flux density of 13.9T.
 

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Jony130

Joined Feb 17, 2009
5,351
But don't forget that Rated Current is not equal to the saturation current. This 16A refers to the "strength" of the wire with which the coil is wound.
 

Thread Starter

Ian0

Joined Aug 7, 2020
5,504
But don't forget that Rated Current is not equal to the saturation current. This 16A refers to the "strength" of the wire with which the coil is wound.
You have a good point, but I would expect that it should operate at its "rated" current, and the current at which it fails would be called the "absolute maximum" current.
 

Thread Starter

Ian0

Joined Aug 7, 2020
5,504
It doesn't specify which rating it is, but it must be the thermal limit.
By my calculations, the inductance-based limit is about 300mA
 

ronsimpson

Joined Oct 7, 2019
2,161
I found many places offering this inductor. Places like ebay not places like DigiKey. One place said it is 10.3mH and 1mH. By looking at the wires size, I think 16A will make it very hot. If the resistance number is accurate that is only 2 watts. The data is so bad I would not trust it.
Normally they will rate the inductance like this. 1mH at 0 current, 0.9mA at 10A, 0.5mH at 16A.
 
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