Additional Installation Tip s
A good solution may be to use a shielded Ethernet cable, but to c o nnect the shield
at one end only.
One option is to break the shield, see 3 in drawing above.
A more elegant method is to expand the shielded Ethernet cabling with a piece of
unshielded Ethernet cable, see 4 in drawing above.
The shield can be grounded via an external 0 .1 μF/250 V film capacitor, see 5 in
drawing above. This connects the HF transients to ground.
7.3 ToAchieveBetterEMCProtection
• Initially, use the original cabling from Beijer Electronics primarily.
• 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 communication cabling.
• Initially, use the original cabling from Beijer Electronics primarily.
• Use shielded cables for RS-232 communication.
• Use twisted pair and shielded cabling for RS-422 and RS-485.
• Use the cabling intended for the bus type; Ethernet, Profibus, CC-Link,
CAN, Device Net etc.
• Use the cabl ing intended for the bus type; Ethernet and CAN
• Install and connect according to applicable specifications for the relevant bus
standard.
• Use shielded cabling for Ethernet, preferably with foil and a braided shield.
• D-sub covers should be shielded, and the shield should be connected to the
cover 360° where the cable enters.
• Connect the shield at both ends.
Shielded cable
Not same potential
Ground plane 1 Ground plane 2
Ground plate Ground plate in another building
0.1 μF/250 V
With longer distances, there is a risk that the ground potential may be different. In
that case, the shield should only be c onnected at one end. A good alternative is to
connect the other end of the shield to the ground via a 0.1 μF/250 V film capacitor.
Both ends are then connected to the ground in terms of HF, but only connected to
the g round at one end in terms of LF, thus avoiding the 50/60 Hz grounding loops.
BeijerElectronics, MAEN330
22
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