Assembling and Installing Systems
A-11
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04
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 connec-
tions, you must interconnectinactive metal parts
such as cabinet doors or support plates via groun-
ding strips or to ground. Use short grounding strips
with a large surface.
2
Supporting bars
Connect the supporting bars and the cabinet hou-
sing over a large area (metal-to-metal connection).
3
Secure the rack
There must be a large-area metal-to-metal connec-
tion 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 con-
ductor and the protective conductor system (groun-
ding point).
Example 2: Wall Mounting for EMC
If you operate your S7-400 in a low-interference environment in which the
permissible ambient conditions are complied with (see 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 surfaces 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.
