C120-H007-08EN 61
5.1 Magnetic Fields
5.1.3 Magnetic field control
Displays may require the following actions to control nearby magnetic fields in
excess of their allowable magnetic field intensities:
(1) Separating the display
Keep the display farther away from sources of magnetic fields. Magnetic fields will
be lessened in a range between the value divided by separation to the third power and
the value divided by separation to the second power.
(2) Changing the display type
Change the display from a CRT display to a liquid-crystal or plasma display.
(3) Magnetic shielding
Special permalloy parts or cases can provide a shield against magnetic field effects.
Certain display models are available with internal fitting magnetic shied options.
For information on magnetic shielding of a display as a whole, consult a shielding
case manufacturer.
DC magnetic field
components
1 Electrically welded metallic exterior sheets, etc.:
Magnetism may remain as a result of metallic
magnetization.
Color misconvergence,
display distortion
2 Magnets used in acoustic equipment: Speaker magnets,
etc.
3 Steel-framed prefabricated columns, etc. moved by an
electromagnetic on a crane
Example: DC magnetic field of 100 at a point 0.5 m
(1.6 ft) away from the steel frame.
4 Equipment operating on a DC magnetic field principle,
a magnetic paper holder, etc.
Example: DC magnetic field of 500 at a point 2 m (7
ft) away from a nuclear magnetic resonance unit
Table 5.1 Sources of magnetic fields and fault symptoms (2/2)
Magnetic field
component
Source of magnetic field Fault symptom
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