Iron sphere AC magnetic field shielding - QuickField simulation example
This is an example of the iron sphere shielding simulation performed with the QuickField software. Example is prepared by Professor James R. Claycomb as a part of the webinar QuickField for Electromagnetic Shielding Applications.
How does the shielding effectiveness of an iron sphere vary with frequency?
Answer Typical applications Geometry
Given
Problem: Solution
Results
Engineering question
Sweep frequency in an axisymmetric AC-magnetic model and calculate the flux density inside the sphere relative to the applied field.
ferromagnetic spherical shields, magnetic shielding spheres, spherical shielding enclosures
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Simulation problem
Problem Type
Axisymmetric problem of AC magnetics.
Relative magnetic permeability of steel μ = 100,
Conductivity of steel σ = 1 MS/m,
External field B = 2.0 T, frequency f = 50 Hz... 100 kHz.
Determine the shielding factor at different frequencies.
LabelMover parametric tool is used to automate frequency sweep. LabelMover generates a set of QuickField problems (multiplying frequency by 2 at each step), simulates problems, calculates the magnetic flux density in the point of interest and place the results in the table.
Magnetic field strength distribution at 50 Hz.
Frequency
Magnetic flux density
inside the spherical shield
50 Hz
267 mT (13%)
800 Hz
24 mT (1.2%)
6.4 kHz
3.3 mT (0.17%)
102.4 kHz
0.13 mT (0.007%)
Video
See more in QuickField for Electromagnetic Shielding Applications webinar.
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