Siemens SIMATIC CN 4100 - Notes on the Reference Potential; Notes on Cable Shields

5.4.4.2 Notes on the reference potential
If the SIMATIC CN 4100 communication system has been con󹪝gured with grounded reference
potential, any interference currents that occur are diverted to the protective conductor/local
ground. A grounding screw contact is used for this.
Note
Grounding screw included in the scope of delivery
The rack is equipped with grounded reference potential. No modi󹪝cation of the supplied unit is
required for grounded reference potential.
Note
Grounding screw no longer accessible
After mounting the rack, the grounding screw is no longer accessible.
Design
The following 󹪝gure shows the con󹪝guration of a system with grounded reference potential:
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① Grounding screw in grounded state
② Metal enclosure of the rack (grounded)
③ Power supply connection
④ Ground potential of the internal circuit
Installation with 󹪞oating reference potential
Installation with 󹪞oating reference potential may only be used in systems with central
grounding.
5.4.4.3 Notes on cable shields
Both ends of the line shielding can be connected to ground (or system ground). This e󹪜ectively
suppresses interference in the high frequency range.
Installation
5.4 Basics for mounting
CN 4100 Communication System
Equipment Manual, 10/2021, A5E50871363-AA 27