[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

# Comparing inductance predictions: femm vs standard formula

- To: <femm@yahoogroups.com>
- Subject: Comparing inductance predictions: femm vs standard formula
- From: "Robert Macy" <macy@california.com>
- Date: Sat, 18 Jan 2003 05:03:52 -0800
- Organization: AJM Electronics
- References: <avn680+1sbr@eGroups.com> <3E1F3465.4050201@ieee.org>
- Reply-to: "Robert Macy" <macy@california.com>

    Not having good results when trying to predict inductance of a multi layer
    solenoid coil.

    dimensions are
    inside radius 0.25 in
    length 1 in
    thickness of coil 0.44 in

    Did femm analysis using asymetric style in a 10 inch diameter sphere with
    over 14k nodes. Then assuming that inductance is 2 times the magnetic field
    energy divided by the total current squared resulted in an inductance
    prediction of 7.638 nH per turn squared.

    However using the formula to predict the inductance of a multilayer solenoid
    from ITT Reference Handbook for Radio Engineers 6th ed which is

    L = 0.8 *(r*N)*r*N)/(6*r+9*length+10*thick)

    produces a prediction of 3.356 nH per turn squared

    Why the huge disparity?

    - Robert -

- Follow-Ups:
  - Re: [femm] Comparing inductance predictions: femm vs standard formula
    - From: David Meeker <dmeeker@ieee.org>

- 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>

- Prev by Date: RE: [femm] Need BH curve for chromium steel
- Next by Date: Re: [femm] Comparing inductance predictions: femm vs standard formula
- Previous by thread: Re: [femm] How is 5 Tesla possible?
- Next by thread: Re: [femm] Comparing inductance predictions: femm vs standard formula
- Index(es):
  - Date
  - Thread