Overview
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A shield room is designed to protect equipment, such as precision equipment,
from external magnetic field by the use of magnetic shielding. In JMAG,
external magnetic field can be specified by the external field condition,
so magnetic flux density distributions both inside and outside the shield
room can be obtained.
This example presents the use of magnetic field analysis to evaluate the
effect of magnetic shielding of a shielded room. |
Magnetic Flux Density Distribution
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Fig. 1 shows the magnetic flux density distribution in the shield room
and surrounding air region.
Since the magnetic flux flows along the wall surface of the shield room
when the external magnetic field is present in the direction of arrows,
the magnetic flux density inside the shield room becomes lower. In addition,
the magnetic flux density becomes higher at the part outlined in red because
the external magnetic field, which is uniform in Z-axis direction, flows
along the wall surface of the shield room, and it becomes lower at the
part outlined in blue. |
Magnetic Flux Density Waveform
Fig. 2 and Fig. 3 show the magnetic flux density waveform at the evaluation
axis A and B.
The shield room is situated at the position between 12 m and 15 m, where
magnetic flux is less dense compared with the other area due to the magnetic
shielding. Compared with the external magnetic field of 50 ƒÊT, the magnetic
flux density inside the shield room is 0.9 ƒÊT. Thus, the effectiveness
of magnetic shielding is about 98 percent. |
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