Motor Cable Shielding; Connection Of Multiple Motors - Danfoss VLT Refrigeration Drive FC 103 Design Manual

System Integration
Motor
U V
2
U V
1
3 3
FC
96 97
Motor
U V
2
U V
1
FC
96 97
Illustration 3.15 Terminal Connection for Clockwise and
Counterclockwise Rotation
Change the direction of rotation by switching 2 phases in
the motor cable or by changing the setting of
parameter 4-10 Motor Speed Direction.

3.5.5 Motor Cable Shielding

Frequency converters generate steep-edged pulses on their
outputs. These pulses contain high-frequency components
(extending into the gigahertz range), which cause
undesirable radiation from the motor cable. Screened
motor cables reduce this radiation.
The purposes of shielding are to:
•
Reduce the magnitude of radiated interference.
•
Improve the interference immunity of individual
devices.
The screen captures the high frequency components and
conducts them back to the interference source, in this case
the frequency converter. Screened motor cables also
provide immunity to interference from nearby external
sources.
Even good shielding does not fully eliminate the radiation.
System components located in radiation environments
must operate without degradation.
56
W
2 2
W
1 1
98
W
2 2
W
1 1
98
Danfoss A/S © 08/2015 All rights reserved.
®
VLT Refrigeration Drive FC 103

3.5.6 Connection of Multiple Motors

NOTICE
Problems may arise at start and at low RPM values if
motor sizes are widely different because small motors'
relatively high ohmic resistance in the stator calls for a
higher voltage at start and at low RPM values.
The frequency converter can control several parallel-
connected motors. When using parallel motor connection,
observe the following:
•
•
•
•
•
•
•
NOTICE
When motors are connected in parallel, set
parameter 1-01 Motor Control Principle to [0] U/f.
Illustration 3.16 Common Joint Connection for Short Cable
Lengths
+
VCC -mode may be used in some applications.
The total current consumption of the motors
must not exceed the rated output current I
the frequency converter.
Do not use common joint connection for long
cable lengths, see Illustration 3.17.
The total motor cable length specified in
Table 3.4, is valid as long as the parallel cables are
kept short (less than 10 m each), see
Illustration 3.19 and Illustration 3.20.
Consider voltage drop across the motor cable, see
Illustration 3.20.
For long parallel cables, use an LC filter, see
Illustration 3.20.
For long cables without parallel connection, see
Illustration 3.21.
for
INV
MG16G202