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CE-EMC Installation Guidelines Section D-1
• Allow the effective shield area of these lines to remain as large as possi-
ble; i.e., do not strip away the shield (screen) further away from the cable
end than absolutely necessary.
• With integrated systems (for example, when the adjustable frequency
inverter is communicating with some type of supervisory controller or host
computer in the same control cabinet and they are connected at the same
ground + PE-potential), connect the shields of the control lines to ground
+ PE (protective earth) at both ends. With distributed systems (for exam-
ple the communicating supervisory controller or host computer is not in
the same control cabinet and there is a distance between the systems),
we recommend connecting the shield of the control lines only at the end
connecting to the adjustable frequency inverter. If possible, route the
other end of the control lines directly to the cable entry section of the
supervisory controller or host computer. The shield conductor of the
motor cables always must connected to ground + PE at both ends.
• To achieve a large area contact between shield and ground + PE-poten-
tial, use a PG screw with a metallic shell, or use a metallic mounting clip.
• Use only cable with braided, tinned copper mesh shield (type "CY") with
85% coverage.
• The shielding continuity should not be broken at any point in the cable. If
the use of reactors, contactors, terminals, or safety switches in the motor
output is necessary, the unshielded section should be kept as short as
possible.
• Some motors have a rubber gasket between terminal box and motor
housing. Very often, the terminal boxes, and particularly the threads for
the metal PG screw connections, are painted. Make sure there is always a
good metallic connection between the shielding of the motor cable, the
metal PG screw connection, the terminal box, and the motor housing. If
necessary, carefully remove paint between conducting surfaces.
6. Take measures to minimize interference that is frequently coupled in
through installation cables.
• Separate interfering cables with 0.25 m minimum from cables susceptible
to interference. A particularly critical point is laying parallel cables over
longer distances. If two cables intersect (one crosses over the other), the
interference is smallest if they intersect at an angle of 90°. Cables suscep-
tible to interference should therefore only intersect motor cables, interme-
diate circuit cables, or the wiring of a rheostat at right angles and never be
laid parallel to them over longer distances.
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