Technical data

Installing bus cables
C.7 Routing electrical bus cables
PROFIBUS Network Manual
272 System Manual, Edition 04/2009, C79000-G8976-C124-03
● Electrical bus cables installed outside buildings must be included in the lightening
protection and grounding concept of the entire system. Please note the information in
Appendix "
Lightning and overvoltage protection of bus cables between buildings
(Page
253)" of this manual.
● All SIMATIC NET PROFIBUS cables can be used if they are installed in cable channels
protected against dampness. In this case, the clearances specified in Section "
Cable
categories and clearances (Page
268)" of this manual must be adhered to.
Underground cabling
Note
Only the SIMATIC NET PROFIBUS underground cable is suitable for direct installation
underground.
If the bus cables are installed directly in the earth, we recommend the following:
● Install the bus cable in a trench.
● Install the bus cable approximately 60 cm below the surface of the ground.
● Mechanical protection must be provided for the bus cables and a cable warning band
should also be included.
● The equipotential bonding between the buildings being connected must be installed
approximately 20 cm above the bus cables (for example a tin-plated strip conductor). The
strip conductor also provides protection against direct lightening strikes.
● When installing bus cables along with other cables, the clearances specified in Section
"
Cable categories and clearances (Page 268)" must be adhered to (for example using
bricks to maintain clearance).
● The clearance to power cables should be ≥ 100 cm if other regulations do not demand a
greater clearance.
C.7.5 Special noise suppression measures
Connecting switched inductances to suppressors
Some inductive switching devices (for example relays) create interference voltages that are
a multiple of the connected operating voltage. The distributed
ET 200 (Page 337) system
manuals contain suggestions about how to limit the interference voltages caused by
inductance by connecting them to suppressors.
Power supply for programming devices
It is advisable to include a power socket for programming devices in each cabinet. The
socket must be supplied by the same system to which the PE conductor for the cabinet is
connected.