The so-called "shielding" in the
cable structure is essentially a measure to improve the distribution of the
electric field. Wires with conductors wrapped around the outside of the
conductor is called shielded wire. Conductors outside the conductor wrapped
wire called shielded wire, wrapped conductors called shielding, generally woven
copper mesh or copper Po (aluminum), shielding needs to be grounded, foreign
interference signals can be imported into the earth by the layer.
Shielded cable is the use of metal mesh
braided layer of the signal line wrapped transmission line, the braided layer
is generally red copper or tinned copper. The shield layer of the shielded
cable needs to be grounded, and foreign interference signals can be directed to
earth by this layer.
Shielded wire is a wire with a metal braided
casing specifically used to reduce the impact of external electromagnetic
fields on power or communication lines. This shield also has the role of
preventing the line from radiating electromagnetic energy to the outside.
Role: to avoid interference signals into the
inner layer, conductor interference while reducing the loss of transmission
signals.
Note: In the selection of shielded wire, the
shield layer grounded conductor insulation layer has a conductive function, can
be conducted with the shield layer (with a certain resistance).
Shielded cable shield is mainly made of
copper, aluminum and other non-magnetic materials, and the thickness is very
thin, much smaller than the skin depth of metal materials on the use of
frequency, the effect of the shield is not mainly due to the metal body itself
on the electric field, magnetic field reflection, absorption and generated, but
due to the grounding of the shield generated, the grounding of different forms
will directly affect the shielding effect. For electric field, magnetic field
shield grounding way is different. Can be used without grounding, single-ended
grounding or double-ended grounding.
Structure wrapped conductor called shielding
layer, generally conductive cloth, woven copper mesh or copper (aluminum)
platinum.
Ordinary cable: insulation layer + shield
layer + conductor.
Advanced cable: insulation layer + shield
layer + signal conductor + shield layer grounding conductor.
Application: shield layer needs to be
grounded, foreign interference signals can be imported into the earth by the
layer, to avoid interference signals into the inner conductor interference
while reducing the loss of the transmitted signal. The role of the shield is to
isolate the electromagnetic field noise source and sensitive equipment, cutting
off the propagation path of the noise source. Shielding is divided into active
shielding and passive shielding, active shielding purpose is to prevent the
noise source outward radiation, is the shielding of the noise source; passive
shielding purpose is to prevent sensitive equipment from being interfered with
by the noise source, is the shielding of sensitive equipment.
Precautions for use: shield wire shield
layer does not allow multiple grounding, because different grounding points are
always different, there is a potential difference between the points. Such as
multi-point grounding, the formation of current in the shield layer, induction
to the wire to form a current, induction to the signal line to form
interference, not only can not play a shielding role, but the introduction of
interference, especially in the frequency converter with more occasions, interference
contains a variety of high harmonic components, resulting in greater impact,
special attention should be paid.
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more EV
HV Cable and electric
vehicle High-Voltage cable, please visit OMG official website: https://www.omgevcable.com/