Motor Connection - Danfoss VLT AutomationDrive FC 300 Design Manual

Electrical Installation
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Illustration 7.11 Mains Connection Frame Size C1 and C2 (IP21/
NEMA Type 1 and IP55/66/NEMA Type 12).
Illustration 7.12 Mains Connection Frame size C3 (IP20).
U
V W
Illustration 7.13 Mains Connection Frame size C4 (IP20).
Usually the power cables for mains are unscreened cables.
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VLT AutomationDrive FC 300 Design Guide, 0.25-75 kW
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MG33BE02 - VLT is a registered Danfoss trademark

7.1.3 Motor Connection

NOTE
To comply with EMC emission specifications, screened/
armoured cables are required. For more information, see
3.5.1 EMC Test Results.
See 4.2 General Specifications for correct dimensioning of
motor cable cross-section and length.
Screening of cables:
Avoid installation with twisted screen ends (pigtails). They
spoil the screening effect at higher frequencies. If it is
necessary to break the screen to install a motor isolator or
motor contactor, the screen must be continued at the
lowest possible HF impedance.
Connect the motor cable screen to both the decoupling
plate of the frequency converter and to the metal housing
of the motor.
Make the screen connections with the largest possible
surface area (cable clamp). This is done by using the
supplied installation devices in the frequency converter.
If it is necessary to split the screen to install a motor
isolator or motor relay, the screen must be continued with
the lowest possible HF impedance.
Cable-length and cross-section:
The frequency converter has been tested with a given
length of cable and a given cross-section of that cable. If
the cross-section is increased, the cable capacitance - and
thus the leakage current - may increase, and the cable
length must be reduced correspondingly. Keep the motor
cable as short as possible to reduce the noise level and
leakage currents.
Switching frequency:
When frequency converters are used together with Sine-
wave filters to reduce the acoustic noise from a motor, the
switching frequency must be set according to the Sine-
wave filter instruction in 14-01 Switching Frequency.
1. Fasten decoupling plate to the bottom of the
frequency converter with screws and washers
from the accessory bag.
2. Attach motor cable to terminals 96 (U), 97 (V), 98
(W).
3. Connect to earth connection (terminal 99) on
decoupling plate with screws from the accessory
bag.
4. Insert plug connectors 96 (U), 97 (V), 98 (W) (up
to 7.5 kW) and motor cable to terminals labelled
MOTOR.
5. Fasten screened cable to decoupling plate with
screws and washers from the accessory bag.
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