Basic Rules - Siemens SIMATIC RF300 System Manual

RF300 system planning
4.6 EMC Directives
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.
● 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-
● Establish a large-area connection between the passive metal parts and the central
● Don't forget to include the shielding bus in the chassis ground system. That means the
● 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 power cables, signal cables and HF cables through separated ducts or in
● 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.
● Routing HF cables:
● Do not route cables through the antenna field.
Shielding for the cables
● Shield the data cables and connect the shield at both ends.
● Shield the analog cables and connect the shield at one end, e.g. on the drive unit.
● Always apply large-area connections between the cable shields and the shielding bus at
● Feed the connected shield through to the module without interruption.
● Use braided shields, not foil shields.
74
The housing or enclosure must be connected to the chassis ground.
impedance contact.
grounding point.
actual shielding busbars must be connected to ground by large-area contact.
separate bundles.
avoid parallel routing of HF cables.
the cabinet inlet and make the contact with clamps.
System Manual, 09/2007, J31069 D0166-U001-A5-7618
SIMATIC RF300