Siemens S5-135U/155U - Manual (Page 37)

3-11
System Manual
C79000-G8576-C199-06
3.2.3 Example of Rack and Wall Mounting for EMC
To operate your control system in a low-interference environment whilst
observing the permissible ambient conditions (see “Technical
Specifications”), you can mount the programmable controllers on racks or
directly on walls.
Picked-up interference should be given a path to large metal surfaces. You
should therefore secure standard sectional rails, shield and protective
conductor bars to metal structural elements. For wall mounting in particular,
installation on reference potential surfaces made of sheet steel has proved
advantageous.
When installing shielded cables, provide a shield bar for connecting the cable
shields. The shield bar can also be the protective conductor bar.
Ensure the following for rack and wall mounting:
S
Suitable contacting aids should be used on painted and anodized metal
parts. Use special contact washers or remove the insulating protective
layers.
S
Provide large-area, low-impedance metal-to-metal connections when
securing the shield/protective conductor bar.
S
AC conductors must be covered.
Shield/Protective
Conductor Bar
Cable Clamp for
Shield Contact
Shielded Signal
Line
Reference Potential
Surface
Connection to
P. Ground: 10 mm
@
Figure 3-3 Wall Mounting of an S5-135/155U PLC
Installation Guidelines