Appendix; Emc-Compatible Installation Of Electrical Industrial Ethernet Or Profibus Cabling; Equipotential Bonding; A.1 Emc-Compatible Installation Of Electrical Industrial Ethernet Or Profibus Cabling - Siemens SCALANCE MM900 Series Compact Operating Instructions

Appendix

A.1 EMC-compatible installation of electrical Industrial Ethernet or
PROFIBUS cabling
The Industrial Ethernet / PROFINET system manual "Passive network components" prescribes
the use of fiber-optic cables for cabling between buildings and/or external facilities because
there may be large potential differences between nodes.
If IE FC or PROFIBUS FC cables are used for such applications, the same rules apply as when
installing cables indoors.
The following also applies:
● Install cables on metal cable racks
● Electrically connect the cable racks where they join
● Ground the cable racks
● Connect the shields of the cables to the grounding network as close as possible to the point
of entry into the building or facility.
● Electrical bus cables installed outside buildings must be included in the lightening protection
and grounding concept of the entire system. Follow the instructions in Appendix B "Lightning
and Surge Voltage Protection for LAN Cables Between Buildings" of the SIMATIC NET
PROFIBUS Networks manual.
● All SIMATIC NET PROFIBUS cables can be used if they are installed in cable channels
protected against dampness. The safety clearances specified in Appendix C.7 "Cable
categories and clearances" of the SIMATIC NET PROFIBUS Network Manual must then be
adhered to.
A.2

Equipotential bonding

When do potential differences occur?
Potential differences can, for example, be caused by different power supplies. Potential
differences between separate parts of the plant can be damaging to the system in the following
situations:
● Programmable controllers and peripheral devices are linked on grounded connections
● Cable shields are contacted at both ends and grounded to different parts of the plant.
How do you avoid potential differences?
Potential differences must be reduced by installing bonding conductors so that the functions of
the electronic components used are guaranteed.
SCALANCE MM900
Compact Operating Instructions, 11/2019, A5E02630805-16
A
65