Siemens SIMATIC RF 300 System Manual page 49

Prevention of interference by optimum configuration
Good interference suppression can be achieved by installing SIMATIC PLCs on conducting
mounting plates (unpainted). When setting up the control cabinet, interference can be
prevented easily by observing certain guidelines. Power components (transformers, drive
units, load power supply units) should be arranged separately from the control components
(relay control unit, SIMATIC S7).
As a rule:
1. The effect of the interference decreases as the distance between the interference source
2. The interference can be further decreased by installing grounded shielding plates.
3. The load connections and power cables should be installed separately from the signal
Figure 4-11
RF 300
System Manual, 05/2005, (4)J31069 D0166-U001-A1-7618, --
and interference sink increases.
cables with a minimum clearance of 10 cm.
Prevention of interference by optimum configuration
RF 300 system planning
4.6 EMC Guidelines
4-33