Motor Integration; Motor Selection Considerations; Sine-Wave And Du/Dt Filters; Proper Motor Grounding - Danfoss VLT AQUA Drive FC 202 Design Manual

System Integration

3.4 Motor Integration

3.4.1 Motor Selection Considerations

3 3
The adjustable frequency drive can induce electrical stress
on a motor. Consider, therefore, the following effects on
the motor when matching motor with adjustable
frequency drive:
•
Insulation stress
•
Bearing stress
•
Thermal stress

3.4.2 Sine-wave and dU/dt Filters

Output filters provide benefits to some motors to reduce
electrical stress and allow for longer cable length. Output
options include sine-wave filters (also called LC filters) and
dU/dt filters. The dU/dt filters reduce the sharp rise rate of
the pulse. Sine-wave filters smooth the voltage pulses to
convert them into a nearly sinusoidal output voltage. With
some adjustable frequency drives, sine-wave filters comply
with EN 61800-3 RFI category C2 for non-shielded motor
cables, see chapter 3.7.5 Sine-wave Filters.
For more information on sine-wave and dU/dt filter
options, refer to chapter 3.7.5 Sine-wave Filters and
chapter 3.7.6 dU/dt Filters.
For more information on sine-wave and dU/dt filter
ordering numbers, refer to and chapter 6.2.9 dU/dt Filters.

3.4.3 Proper Motor Grounding

Proper grounding of the motor is imperative for personal
safety and to meet EMC electrical requirements for low
voltage equipment. Proper grounding is necessary for the
effective use of shielding and filters. Design details must
be verified for proper EMC implementation.

3.4.4 Motor Cables

Motor cable recommendations and specifications are
provided in chapter 7.5 Cable Specifications.
All types of three-phase asynchronous standard motors can
be used with an adjustable frequency drive unit. The
factory setting is for clockwise rotation with the adjustable
frequency drive output connected as follows:
58
®
VLT AQUA Drive FC 202
Motor
U
2
U
1
FC
96
Motor
U
2
U
1
FC
96
Figure 3.10 Terminal Connection for Clockwise and Counter-
clockwise Rotation
Change the direction of rotation by switching two phases
in the motor cable or by changing the setting of
4-10 Motor Speed Direction.

3.4.5 Motor Cable Shielding

Adjustable frequency drives 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. Shielded
motor cables reduce this radiation.
The purposes of shielding are to:
•
•
The shield captures the high-frequency components and
conducts them back to the interference source, in this case
the adjustable frequency drive. Shielded motor cables also
provide immunity to interference from nearby external
sources.
Danfoss A/S © 09/2014 All rights reserved.
V W
2 2
V W
1 1
97 98
V W
2 2
V W
1 1
97 98
Reduce the magnitude of radiated interference.
Improve the interference immunity of individual
devices.
MG20N622