Siemens SIMATIC NET PROFIBUS, Owner'S Manual

Page: 278 / 490

Installing LAN Cables
C-16
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
C.5.2 Cabling within Closets
When cabling within wiring closets, note the following points:
S
The minimum clearance between cables of different categories can be found in
Table C-1. In general, the risk of interference due to crosstalk is less the
greater the clearance between the cables.
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Where cables of different categories cross, they should cross at right angles
(keep sections where the cables run parallel as short as possible).
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If there is not enough space to maintain a clearance
≥
10 cm, the cables should
be arranged according to their categories in separate metal, conductive
channels. These channels can then be arranged next to each other. The metal,
conductive channels should be screwed to the struts of the rack or the closet
walls making low-resistance and low-inductance contact.
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The shields of all cables entering the wiring closet must be secured as close as
possible to the point of entry and should make large-area contact with closet
ground.
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Parallel routing of incoming cables and internal closet wiring between the point
of entry into the closet and the shield clamp should be avoided at all costs even
with cables of the same category.
C.5.3 Cabling within Buildings
When laying cables outside cabinets but within buildings, note the following points:
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The clearances listed in Table C-1 must be maintained between the various
cable categories and when laying cables on common cable racks.
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If the cables are laid in metal cable channels, the channels can be arranged
directly beside each other.
If there is only one common metal channel available for all categories, either the
clearances shown in Table C-1 must be maintained or if this is not possible for
lack of space, the individual categories should be separated from each other by
metallic partitions. The partitions must be connected to the channel making
low-resistance and low-inductance contact.
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Cable racks should cross each other at right angles.
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Include metal, conducting cable channels/racks in the equipotential bonding of
the building and between the individual parts of the system.
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Note the information on equipotential bonding in Section C.4.4 in this manual.