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Main >> Applications >> Sample problems >> Electromagnetic Screen
Multilayered shield protects the equipment from the external highfrequency electromagnetic field. The shield should work in wide range of temperatures. Calculate the shielding coefficient as a function of temperature.
Problem Type:
An axisymmetric problem of nonlinear Heat transfer coupled to AC magnetics.
Geometry:
Given:
Magnetic permeability of the shields μ = 1;
Conductivity of the shields σ  depends on temperature, as shown on the plot below;
External field B = 0.03 T;
Frequency f = 4000 Hz;
Temperature range T = 100.. +100 °C;
Device temperature T = 20 °C.
Problem:
The shield conductivity depends on temperature. Calculate the shielding coefficient as a function of temperature.
Solution:
The thermal problem is solved for obtaining the temperature distribution. The result of simulation is transferred to AC magnetics problem, where the magnetic field distribution is calculated. Average flux density is calculated in the 'device' block. Shielding coefficient is then calculated as a ratio of the flux densities on both sides of the screen.
The external magnetic field is defined by the boundary conditions.
Results:
Temperature distribution in the screen:
Temperature 
Flux density in device 
Shielding coefficient 
100 °C 
1.0e8 T 
3.3e7 
0 °C 
5.2e8 T 
17.3e7 
100 °C 
2.8e7 T 
93.3e7 
Magnetic field in the screen:
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