Notes On The Reference Potential; Notes On Cable Shields - Siemens SIMATIC CN 4100 Equipment Manual

5.4.4.2

Notes on the reference potential

If the SIMATIC CN 4100 communication system has been configured 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 modification 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 figure shows the configuration of a system with grounded reference potential:
①
②
③
④
Installation with floating reference potential
Installation with floating 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 effectively
suppresses interference in the high frequency range.
CN 4100 Communication System
Equipment Manual, 10/2021, A5E50871363-AA
Grounding screw in grounded state
Metal enclosure of the rack (grounded)
Power supply connection
Ground potential of the internal circuit
Installation
5.4 Basics for mounting
27