Beijer Electronics EXTER K20m EN - Manual (Page 23)

Additional Installation Tips
Beijer Electronics, MAEN852A 23
6.3 To Achieve Better EMC Protection
– Initially, use the original cabling from Beijer Electronics primarily.
– Use shielded cables for RS232 communication.
– Use twisted pair and shielded cabling for RS422 and RS485.
– Use the cabling intended for the bus type; Ethernet, Profibus, CC-Link, CAN,
Device Net etc.
– Install and connect according to applicable specifications for the relevant bus stan-
dard.
– Use shielded cabling for Ethernet, preferably with foil + braided shield.
– D-sub covers should be shielded, and the shield should be connected to the cover
360 ° where the cable comes in.
– Connect the shield at both ends.
With longer distances, there is a risk that the ground potential may be different. In
that case, the shield should only be connected at one end. A good alternative is to
connect the other end of the shield to the ground via a 0.1 uF/250 V plastic capacitor.
Both ends are then connected to the ground in terms of HF, but only connected to
the ground at one end in terms of LF, thus avoiding the 50 Hz grounding loops.
– Use an EMC cable gland or regular plastic cable gland, remove the outer jacket
and connect the shield to the installation plate with a 360 ° metal cable clamp.
– Place the 24 V DC and communications cabling in one cable trunk/cable duct and
230/380 V AC in another. If the cables need to be crossed, cross them at 90 ° only.
Avoid combining the cabling for stronger 24 V DC outputs with the communi-
cation cabling.
– Ferrite cores that are snapped onto the shielded cabling may remove minor distur-
bances. Large ferrite pieces that are snapped onto unshielded cabling and where
the wires go 2-4 times around the cores are approximately 5-25 times more effi-
cient.
5352
Shielded cable
Ground plane 1 Ground plane 2
Ground plate Ground plate
in another building
0.1 uF/250 V
Not same potential
5353
Metal cabinet Metal cabinet
Terminal or
connector
Terminal or
connector
EMC cable gland Plastic cable gland
Shielded cable Shielded cable
Cable clamp
in steel
Sho
rt d
is
tanc
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