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# Re: [femm] How is 5 Tesla possible?

- To: femm@yahoogroups.com
- Subject: Re: [femm] How is 5 Tesla possible?
- From: Dave Squires <djsquires@plix.com>
- Date: Mon, 13 Jan 2003 09:27:03 -0800
- References: <avn680+1sbr@eGroups.com> <3E1F3465.4050201@ieee.org> <5.1.0.14.0.20030113140247.01dc0b20@staff-mailin.lboro.ac.uk> <000201c2bb23$45715560$497b5142@robertmacy>
- User-agent: Mozilla/5.0 (Windows; U; Win 9x 4.90; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0

    Check the BH curve of the core material.
    Does it take into account saturation correctly?
    What is the effective mu and what effective H
    do you see in those areas?

    I find that if you get the BH curve to be extended
    into the saturation region correctly that you start
    to see the flux leakage you would expect and the
    flux density is better behaved.
    Otherwise you can see ridiculous numbers like even
    40 or 50 tesla or more. Try to put more points
    that are more realistic on the BH curve out into
    the high H regions. That should help some. Otherwise
    FEMM will just extrapolate at the previous slope
    of an unrealistic mu higher than what it should be.

`DRS`
`Robert Macy wrote:`

> `Just downloaded and ran it. Got 8 to 9 Teslas in the tight areas.`
> `??`
> `- Robert -`

>     ----- Original Message -----
>     From: Keith Gregory
>     To: femm@yahoogroups.com
>     Sent: Monday, January 13, 2003 6:11 AM
>     Subject: Re: [femm] How is 5 Tesla possible?

> `
> Robert,`

>     Harmonic problems (i.e. where frequency is not zero) are solved linearly by
>     FEMM, it doesn't include saturation so any value of B can be achieved. Dave
>     has recently produced a development version which can deal with non-linear
>     problems, which is (I think) currently version 3.3alpha2.

>     http://femm.berlios.de/femm33src.zip
>     http://femm.berlios.de/femm33bin.exe

> `Try that.`
> `Keith.`
> `At 23:22 12/01/2003 -0800, you wrote:`

> > `Apologize for the stupidity here, but...`
> > `How is 5 Tesla possible? in mumetal that saturates at 0.6T?`

> >     While doing a simple analysis using mumetal I found that at 100KHz the
> >     material displayed the expected skin depth effects, but the |B| magnitude
> >     fields were more than 5 teslas.

> > `How is this possible?`
> > `- Robert -`
> > ``
> > ``
> > ``
> > `Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/`

> ``

>     Dr. Keith Gregory
>     Senior Lecturer
>     Department of Electronic & Electrical Engineering
>     Loughborough University
>     Loughborough
>     Leicestershire
>     LE11 3TU
>     UK

>     Phone: +44 (0) 1509 227025 Fax: +44 (0) 1509 227014
>     Department web: http://www.lboro.ac.uk/departments/el/

> ``

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``
``

- Follow-Ups:
  - Re: [femm] How is 5 Tesla possible?
    - From: "Robert Macy" <macy@california.com>

- References:
  - Alnico 8 relative permeability
    - From: "sloothrog <salvarsan@std.com>" <salvarsan@std.com>
  - Re: [femm] Alnico 8 relative permeability
    - From: David Meeker <dmeeker@ieee.org>
  - Re: [femm] How is 5 Tesla possible?
    - From: Keith Gregory <k.gregory@lboro.ac.uk>
  - Re: [femm] How is 5 Tesla possible?
    - From: "Robert Macy" <macy@california.com>

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