Siemens RS-485 Wartungshandbuch PDF herunterladen (Seite 271)

Installing bus cables

C.7 Routing electrical bus cables

PROFIBUS Network Manual

System Manual, Edition 04/2009, C79000-G8976-C124-03

271

C.7.3 Cabling within buildings

What do I need to remember?

When laying cables outside cabinets but within buildings, note the following points:

● The clearances listed in Section "

Cable categories and clearances (Page 268)" must be

maintained between the various cable categories and when laying cables on common

cable racks

● 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 Section "

Cable categories and clearances (Page 268)" 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 lowresistance and lowinductance contact.

● Cable racks should cross each other at right angles.

● Include metal, conductive cable channels/racks in the equipotential bonding of the

building and between the individual parts of the system.

● Note the information on equipotential bonding in Section "

Equipotential bonding

(Page

267)" in this manual.

C.7.4 Cabling outside buildings

Fiberoptic cables should be given preference

For communications between buildings and between buildings and external facilities, the use

of fiberoptic cables is generally recommended. Due to the optical transmission principle,

fiberoptic cables are not affected by electromagnetic interference. Measures for equipotential

bonding for overvoltage protection are unnecessary with fiberoptic cables.

EMC rules for electrical bus cables

When installing electrical bus cables outside buildings, the same EMC rules apply as for

cables inside buildings. In addition, the following applies:

● Install cables on metal cable racks

● Electrically connect the cable racks where they join

● Ground the cable racks

● There must be adequate potential equalization between buildings and external facilities

regardless of the bus cables. (see Section "

Equipotential bonding (Page 267)")

● The cables should be installed as close as possible and parallel to the equipotential

bonding.

● Connect the shields of the cables to the grounding network as close as possible to the

point of entry into the building or facility.

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