Implementation shielding practice
With the KLBUE, Weidmueller has developed versatile
product designed reduce EMV plants and equipment. capacitor
is often connected the reference potential one side to
reduce such interference.
The interference expected
determines the shield connection
In order suppress electric fields, one-sided ground-
ing the shield necessary.
to improve machines.
Coupling mechanisms:
Galvanic coupling
Coupling two circuits via common current path.
In addition natural sources interference such lightning, there are also
so-called coupling mechanisms.
Inductive (magnetic) coupling
Coupling two circuits via alternating magnetic field
(mainly the low-frequency range).
However, the shield connected both sides, ground
loop occurs, which turn has disadvantages.
Use shielded cables
The task electromagnetic screen close its
internally generated electromagnetic field and prevent
it from propagating create space free external
fields.
Capacitive (electrical) coupling
Coupling two circuits via alternating electric field
(mainly the high-frequency range)..Application
range
Shielding and earthing
Actions:
Measures improve electromagnetic compatibility
In order guarantee EMC, the interference mechanisms must first known. suppress alternating
magnetic field, the shield must grounded both sides.
B. this
case, triaxial cables can help connecting the inner shield
on one side and the outer shield both sides.
Radiation coupling (electromagnetic coupling)
Emission wave fields with electric and magnetic field
strength. The useful
signal influenced particular interference along the
reference potential and thus deterioration occurs. Here overview the different coupling
mechanisms well some measures for EMC optimisation. This interrupts the earth loop for
direct currents low-frequency currents.
Measures for EMC optimisation:
The most frequently used and sensible countermeasures to
improve EMC are the use twisted shielded cables.261
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