NORD Drivesystems BU0220 - Manual (Page 77)

8 Additional information
BU 0220 GB-0912 Subject to technical amendments 77
NOTE
The lower the shielding resistance of the PROFIBUS DP cable, the better the EMC quality.
The electromagnetic compatibility (EMC) describes the normally required state, that
technical devices do not interfere with each other due to electrical or electromagnetic
effects.
8.1.3 Cable layout and shielding (EMC measures)
If EMC measures are not in place, high-frequency interference which is mainly caused by switching processes
or lightning often causes electronic components in the bus subscribers to be faulty and error-free operation can
no longer be ensured.
Appropriate shielding of the bus cable reduces electrical interference which can arise in an industrial
environment.
The best shielding characteristics are achieved with the following measures:

Do not make cable connections shorter than 1m between bus participants

Avoid long connections between bus subscribers

Shield the bus cable on both ends with large-area connection to the plug housing

Avoid spur lines (above 1.5MBaud spur lines are no longer permissible)

Avoid extensions to bus cables via plug connectors
Bus lines should be laid with a minimum spacing of 20cm to other lines which carry a voltage higher than 60V.
This applies to lines laid inside and outside of control cabinets.
Special attention should be paid to bending radii:
Fixed cable Freely laid cable Bending radius of cable
Minimum radius
5 x cable diameter
Minimum radius
10 x cable diameter
Correct Incorrect
NOTE
If earthing potential values are different, transient current may flow through shielding which
is connected on both sides. This may be a danger to electronic components. Differences in
potential must be reduced by means of adequate potential equalisation.