Danfoss VLT FC 300 Instruction Manual page 51

VLT ® Automation Drive FC 300
Instruction Manual High Power
See section General Specifications for correct dimensioning of motor cable cross-section and
length.
Shielding of cables:
Avoid installation with twisted shield ends (pigtails), as they reduce the shielding effect at higher
frequencies. They spoil the shielding effect at higher frequencies. If it is necessary to break the
shield to install a motor isolator or motor contactor, the shield must be continued at the lowest
possible HF impedance.
Connect the motor cable shield to both the de-coupling plate of the adjustable frequency drive
and to the metal housing of the motor.
Make the shield connections with the largest possible surface area (cable clamp). This is done by
using the supplied installation devices in the adjustable frequency drive.
Cable length and cross-section:
The adjustable frequency drive 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, thereby requiring that the cable length is reduced accordingly. Keep the
motor cable as short as possible to reduce the noise level and leakage currents.
Details can be found in the relevant Design Guide.
Switching frequency:
When adjustable frequency drives are used together with sine-wave filters to reduce the acoustic
noise from a motor, the switching frequency must be set according to the instructions in par.
14-01.
Term.
no.
1)
Protected Ground Connection
NOTE
Motor cable must be shielded/armored. The use of an unshielded/unarmored cable
is against EMC requirements. Use a shielded/armored motor cable to comply with
EMC emission specifications. For more information, see
Design Guide
.
96 97 98 99
U V W 1)
PE
U1 V1 W1
PE 1)
W2 U2 V2
U1 V1 W1 PE 1)
MG.33.U1.22 - VLT ® is a registered Danfoss trademark.
EMC specifications
Motor voltage 0-100% of line voltage.
3 wires out of motor
Delta-connected
6 wires out of motor
Star-connected U2, V2, W2
U2, V2 and W2 to be interconnected separately.
NOTE
In motors without phase insula-
tion paper or other insulation re-
inforcement suitable for opera-
tion with voltage supply (such
as an adjustable frequency
drive), fit a sine-wave filter on
the output of the adjustable fre-
quency drive.
3. How to Install
in the
3
51