Planning the MOBY D system
4.5 EMC Guidelines
MOBY D
70 System Manual, 01/2010, J31069-D0147-A6-7618
4.5.3 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
● Plan a meshed grounding concept.
● 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 power cables, signal cables and HF 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.
● Routing HF cables:
avoid parallel routing of 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
the cabinet inlet and make the contact with clamps.
● Feed the connected shield through to the module without interruption.
● Use braided shields, not foil shields.
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