2-28
2-2 Wiring
2
Design
Direct connection as much as possible: Direct connection to the communications port of the
control unit is mandatory to reduce connection impedance. This is very important, if there is a long
distance between the system and you expect there can be different PE-Potential between the
systems.
Shield surface maximization: The effective shield area of these lines to remain as large as
possible; i.e., do not move the shield of conductors further away than absolutely necessary. Avoid
pigtails as much as possible. Avoid long unshielded cable runs.
Control system in the same cabinet - Connect shield in both sides, never midway: All analog
and digital control lines are laid shielded. With compact systems, if the frequency inverter and the
control unit area in the same control cabinet connected at the same PE-Potential, the screen should
be connected on both sides of the cable with PE (potential is same).
Control system in separate cabinet - Connect shield only one side: All analog and digital
control lines are laid shielded. With distributed systems, if the communications control unit is not in
the same cabinet and there is a distance between the systems, we recommend to put the screen
only on the side of the frequency inverter, to avoid ground loops beacuse different PE potential.
Distance between sensitive signals and interference sources: The distance between an inter-
ference source and an interference sink (interference-threatened device) essentially determines the
effects of the emitted interference on the interference sink. The interference field emitted by the
frequency inverter falls sharply with increasing distance. Please note that the emitted interference
field (frequency range 30 MHz - 1 GHz) of a drive (drive system) is measured at a distance of 10 m
in accordance with EN61800-3. Every device placed closer than 10 m to a source of interference
will thus be impacted by appreciably higher interference amplitudes. For this reason, you should use
only interference-free devices and mantain a minimum distance of 0.25 m from the drive. Devices
which react sensitively to interference from electric and magnetic fields should be kept at least a
distance of 0.25 m from the following components:
•Frequency inverter
•EMC input/output filters
•Input or output reactors/transformer
•Motor cable (even if shielded)
•External braking resistor and its wiring (even if shielded)
•AC/DC commutator motors, including any attached separate fans
•DC intermediate circuit coupling/wiring (even if shielded)
•Connected inductors like relays, contactors, solenoid valves, brakes (even if shielded)
Avoid parallel runs of power and control lines: The parallel running in same conduit without
proper distance of power lines (even shielded cables) and control lines is not allowed. This is source
of most of EMC disturbance coupling.
Crossing power lines and control lines: Should power and control lines have to cross unavoid-
ably each other, then they should be layout with a 90º crossing.
Control cables
Motor power cable
Control
cables
Motor power
cable
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