Assembling and Installing Systems
A-11
Automation System S7-400 Hardware and Installation
A5E00850741-01
Key for example 1
The numbers in the following list refer to the numbers in Figure A-2.
Table A-1 Key for Example 1
No. Key Meaning
1 Grounding strips If there are no large-area metal-to-metal
connections, you must interconnectinactive metal
parts such as cabinet doors or support plates via
grounding strips or to ground. Use short grounding
strips with a large surface.
2 Supporting bars Connect the supporting bars and the cabinet
housing over a large area (metal-to-metal
connection).
3 Secure the rack There must be a large-area metal-to-metal
connection between supporting barand rack.
4 Signal lines Use cable clamps on the protective ground bar or an
additional shield bus forlarge-area connection of the
shield of signal lines.
5 Cable clamp The cable clamp must surround the braided shield
over a large area and ensuregood quality contact.
6 Shielding bus Provide a large-area connection between the shield
bus and supporting bars (metal-to-metal
connection). The cable shields are connected to the
shield bus.
7 Protective ground
bar
Provide a large-area connection between the protec-
tive ground bar and supporting bars (metal-to-metal
connection). Connect the protective ground bar to
the protective conductor system via a separate con-
ductor (minimum cross-section 10 mm
2
).
8 Conductor to the
protective conductor
system (grounding
point)
Provide a large-area connection between the
conductor and the protective c onductor system
(grounding point).
Example 2: EMC--compliant Wall Mounting
If you operate your S7-400 in a low-interference environment in which the
permissible ambient conditions are c omplied w ith (see the Module Data reference
manual, Chapter 1), you can mount your S7-400 in frames or on the wall.
Picked-up interference must be given a path to large metal surfaces. You should
therefore secure standard mounting channels, shield, and protective ground bars to
metal structural elements. For wall mounting in particular, installation on reference
potential s urfaces made of sheet steel has proved advantageous.
Provide a shield bus for connecting the cable shields if you install shielded cables.
The shield bus can simultaneously serve as the protective ground bar.
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