MG.20.B6.02 – VLT is a registered Danfoss trademark
VLT
®
2000 Series
88
Special conditions
A flat conductor, for example, has a lower HF
impedance than a round conductor for the same con-
ductor square value.
If more than one applicance is installed in cabinets,
the cabinet rear plate, which must be made of metal,
should be used as a common earth reference plate.
The metal cabinets of the different appliances are
mounted on the cabinet rear plate using the lowest
possible HF impedance. This avoids having different
HF voltages for the individual appliances and avoids
the risk of radio interference currents running in
connection cables that may be used between the
appliances. The radio interference will have been
reduced.
cable). It must be pointed out that the necessary di-
stance depends on the sensitivity of the installation
and the signal cables, and that therefore no precise
values can be stated.
If cable trays are used, sensitive signal cables are not
to be placed in the same cable trays as the motor
cable or brake cable.
If signal cables are to cross power cables, this should
be done at an angle of 90 degrees.
Remember that all interference-carrying in- or
outgoing cables to/from a cabinet should be
screened or filtered.
The cables must throughout their length be
reinforced/double-isolated to other cables.
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Earthing
The following basic issues need to be considered
when installing a frequency converter, so as to obtain
electromagnetic compatibility (EMC).
Safety earthing:
Safety earthing:
Safety earthing:
Safety earthing:
Safety earthing:
Please note that the frequency converter has a high
leakage current and must be earthed appropriately for
safety reasons. Apply local/national safety regulations.
Use terminal 95 for reinforced earthing.
High fr
High fr
High fr
High fr
High frequency earthing
equency earthing
equency earthing
equency earthing
equency earthing:
Keep the earth wire connections as short as possible.
Connect the different earth systems at the lowest
possible conductor impedance.
The lowest possible conductor impedance is obtained
by keeping the conductor as short as possible and by
using the greatest possible surface area.
Cables
The control cable and the filtered mains cable should
be installed separately from the motor and brake
cables to prevent interference coupling. Normally, a
distance of 20 cm will be sufficient, but it is
recommended to keep the greatest possible distance
wherever possible, especially where cables are
installed in parallel over a substantial distance.
With respect to sensitive signal cables such as
telephone cables and data cables, the greatest
possible distance is recommended with a minimum of
1 per 5 m of power cable (mains, motor and brake
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