RF300 system planning
4.6 EMC Directives
SIMATIC RF300
System Manual, Release 04/2006, J31069 D0166-U001-A2-7618
4-45
4.6.3 Basic rules
It is often sufficient to follow a few elementary rules in order to ensure electromagnetic
compatiblity (EMC).
The following rules must be observed:
Shielding by enclosure
• Protect the device against external interference by installing it in a cabinet or housing.
The housing or enclosure must be connected to the chassis ground.
• Use metal plates to shield against electromagnetic fields generated by inductances.
• Use metal connector housings to shield data conductors.
Wide-area ground connection
• Bond all passive metal parts to chassis ground, ensuring large-area and low-HF-
impedance contact.
• Establish a large-area connection between the passive metal parts and the central
grounding point.
• Don't forget to include the shielding bus in the chassis ground system. That means the
actual shielding busbars must be connected to ground by large-area contact.
• Aluminium parts are not suitable for ground connections.
Plan the cable installation
• Break the cabling down into cable groups and install these separately.
• Always route high-voltage and signal cables through separated ducts or in separate
bundles.
• Feed the cabling into the cabinet from one side only and, if possible, on one level only.
• Route the signal cables as close as possible to chassis surfaces.
• Twist the feed and return conductors of separately installed cables.
• Cable routing of HF cables:
Avoid installing cables in parallel over long distances and maintain minimum distances
between the cables (at least 25 cm).
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