Beijer Electronics BoX2 extreme, Installation Manual

Page: 23 / 28

Additional Installation Tips
A good solution may be to use a shielded Ethernet cable, but to connect 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.
6.3 To Achieve Better EMC Protection
•
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.
•
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 μ F/250 V
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 μF/250 V film 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 50/60 Hz grounding loops.
Metal cabinet Metal cabinet
Terminal or connector Terminal or connector
EMC cable gland
Plastic cable gland
Shielded cable
Short distance
Cable clamp
in steel
Shielded cable
1. 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.
Beijer Electronics, MAEN274 23