Baumuller BUM64A, Manual

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EMC requirements on cable routing (EMC information)
Manual Single Power Unit BUM64S/A/F
Document no.: 5.01056.03
Baumüller Nürnberg Electronic GmbH & Co. KG
56
of 118
6.7
h form a good conductive connection of the cable screens where the cable enters the
housing.
h take care that the distance of the last screen contact point to the exit of the cabinet
must be as short as possible.
figure 20: Screening of cables at switching cabinet exit
6.7.2.3 Screening
The screening is effective against magnetic fields if the screen is connected to ground on
both ends.
With electrical fields, the screen is effective when it is connected to ground at only one
end.
h however, in case of (both electrical or magnetic) fields with high frequencies (depend-
ing on the length of the line), you must always connect the screen at both ends.
figure 21: Screen contact on both sides of a line
Connecting the screen to ground at both ends ensures that the conductor does not “leave
the system housing“.
Grounding of conductor screens on both sides does not entirely rule out the influence of
earth circuits (potential differences on the ground system). Those are very rare, if you car-
ry out the measures described in the previous sections entitled (
Z Cabling – from page 53)
and ( Z Grounding – from page 55).
You can also form a capacitive RF connection of a screen to ground. This prevents low-
frequency interference due to earth circuits.
h screened cables that are routed through different EMC areas must not be interrupted
at terminals, since screen damping would otherwise be reduced considerably.
h if possible, run the cables without interruption to the next module.
h carry out the screen connection low-impedant and use a wide surface.