VLT
®
5000 Series
■ Installation of motor cables
NB!:
If an unscreened cable is used, some EMC
requirements are not complied with, see the
Design Guide.
If the EMC specifications regarding emission
are to be complied with, the motor cable must be
screened, unless otherwise stated for the RFI filter in
question. It is important to keep the motor cable as
short as possible so as to reduce the noise level and
leakage currents to a minimum.
The motor cable screen must be connected to
the metal cabinet of the frequency converter and to
the metal cabinet of the motor. The screen connec-
tions are to be made with the biggest possible
surface (cable clamp). This is enabled by different
installation devices in the different VLT frequency
converters.
Mounting with twisted screen ends (pigtails) is to be
avoided, since these spoil the screening effect at
higher frequencies.
If it is necessary to break the screen to install a mo-
tor isolator or motor contactor, the screen must be
continued at the lowest possible HF impedance.
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 ca-
ble capacitance — and thus the leakage current —
increases, and the cable length must be reduced
correspondingly.
■ Connection of motor
All types of 3-phased asynchronous standard motors
can be used with the VLT 5000 Series.
Normally, small motors are star-connected (200/400
V,
1
/Y).
Large motors are delta-connected (400/690 V,
1
/Y).
■ Direction of motor rotation
The factory setting is for clockwise rotation with the
VLT frequency transformer output connected as fol-
lows.
Terminal 96 connected to U-phase
Terminal 97 connected to V-phase
Terminal 98 connected to W-phase
The direction of rotation can be changed by switch-
ing two phases in the motor cable.
■ Parallel coupling of motors
VLT 5000 Series is able to control several motors
connected in parallel. If the motors are to have dif-
ferent rpm values, the motors must have different
rated rpm values. Motor rpm is changed simultane-
ously, which means that the ratio between the rated
rpm values is maintained across the range.
MG.51.A1.02 - VLT is a registered Danfoss trade mark
63
Installation
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