5.3 Frequency inverter and EMC
Interference emission and installation of cables
•
In order to prevent faults attributable to interference and to ensure compliance with
the radio interference level, the connecting leads must be kept as short as possible
both in the motor terminal box as well as in the controller. Spacing between supply
cables, motor cable and signal cable should thereby be kept as large as possible.
•
When laying shielded lines, never use so-called "pigtails" on shields (twisting of the
shielding braid into strands).
•
EMC screwed connections must be used on cable entries.
•
High-frequency earthing of the complete drive system must be carried out on both
sides on the motor and the inverter in a technically correct manner. Implement a
contacting process on a large-scale for good discharge of high-frequency currents for
a 360
°
contacting process by means of EMC shield clips on the inverter and an EMC
screwed connection on the motor.
•
Make sure that the cable gland has an electro-conductive connection to the
terminal box. If necessary, the available coating must be removed on the
contact point or a tooth lock washer used on the counter ring.
•
Maintenance or emergency switches installed between inverter and motor must
also be shielded.
•
Please observe the corresponding installation instructions of the frequency
inverter that is used!
Reducing bearing currents when operating on the inverter
•
When operating on the inverter harmful bearing currents can occur in the motor. This
depends on many factors which, in many cases, ZIEHL-ABEGG cannot in
fl
uence.
Thus, it comes down to the expert installation in the respective assembly situation.
The following points serve as a guideline, but cannot always prevent bearing currents
from occurring.
•
To systematically reduce and prevent damage by bearing currents, you must take into
account the overall system made up of motor and inverter. But further additional
measures may be necessary, e.g. use of all-pole sinusoidal
fi
lters or use of hybrid
bearings.
•
The ZIEHL-ABEGG Fcontrol frequency inverter is already geared to
ZIEHL-ABEGG motors and possesses an all-pole sinusoidal
fi
lter so that no
harmful bearing currents at all can be expected with the correct installation.
Frequency inverter, external brand
The following measures support the reduction of harmful bearing currents:
•
The speci
fi
ed measures with regard to EMC-compatible installation must be observed
and implemented.
•
For electrical bridging of vibration dampers, use high-frequency equipotential bonding
conductors made of braided
fl
at copper strips with a minimum cross-section of
16mm
²
.
•
Design the contacting process on a large-scale.
•
Use shielded connecting cables with as symmetrical a design as possible.
•
Connect the screen on both sides on the motor and inverter.
Assembly instructions
MAXvent
Electrical installation
L-BAL-F054-GB 2018 Index 005
Part.-No. 00501414-GB
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