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# core saturation with perm. magnets

## core saturation with perm. magnets

(OP)
Hi, I am new here and magnetism is not my best side. I need an answer on the following:

question 1:
I have a "U" transformer form with a cross section of 85mm X 35mm, The saturation inductance is 1.56T (15.6 Kgauss) Now I want to put a permanent with a cross section of 85mm x 35mm between the end of the legs of the "U". What permanent magnet do i need to just saturate the metal of the "U" and how do I calculate that?

Question 2:
I need also to replace this permanent magnet with a electro magnet so that it shows the same saturation. how do i calculate the number of turns for the wire (dc and ac 50Hz)

Question 3 To saturate the same "U" but pulsed with 24v DC, how would I go ahead to calculate this.

It is important that the power use is as efficient as possible in all different cases. Can I change the power usage by changing the applied voltage for the same saturation?

This is a big slice of bread, But for you magnetic people this is nothing.

I thank you for the answer,

Willy

Replies continue below

### RE: core saturation with perm. magnets

Are you a student?

(OP)
No, i am retired

Willy

### RE: core saturation with perm. magnets

If you look at the PM option:  You are after 15.6 in a closed circuit, so you are working at Br for the PM.  Since you won't find values over 12.5 (for Alnico 5) you will need a cross section of magnet that is 15.6/12.5 larger than the core, and you will need tapered pole pieces to bring it all together.  And you have to keep your pole pieces from saturating also.

The elcetromagnet is simple physics.  Amps times turns, times the right conversion factors.

In pulse mode you do the same, but the trick is knowing the peak current, and making sure that the pulse is long enough to get saturation.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

### RE: core saturation with perm. magnets

(OP)
Thank you EdStainless, that solves already allot. it is 50 years ago that I did dis and not using it in this 50 years, I forgot almost all

What is the "the right conversion factors. Is this also the 15.6/12.5?

Thank you again.

Willy

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