VLT
®
8000 AQUA
Introduction
VLT 8000 AQUA is available with an integral serial communication option or application option. Ordering
numbers for the individual VLT types with integrated options can be seen from the relevant manuals or
instructions. In addition, the ordering number system can be used for ordering an adjustable frequency
drive with an option.
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Cascade Controller Option
In "Standard Mode", one motor is controlled by the
drive that has the Cascade Controller Option card
installed in it. Up to four additional fixed speed
motors can be sequenced on & off, as required
by the process, in lead-lag mode.
In "Master/Slave Mode", the drive that has the
Cascade Controller option card installed in it, along
with its associated motor, is designated as the
master. Up to four additional motors, each with its
own drive, can be operated in slave mode. The
Cascade Controller functions to stage the slave
drives/motors - on & off (as required), as a function
of "best system operating efficiency".
In "Lead Pump Alternation Mode", it is possible to
average out the usage of the pumps. This is done by
making the frequency converter switch between the
pumps (max. 4) by means of a timer. Please note
that this mode requires an external relay setup.
Consult your Danfoss Sales Office for
additional information.
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LC filters for VLT 8000 AQUA
When a motor is controlled by an AFD, resonance
noise will be heard from the motor. This noise, which is
caused by the design of the motor, occurs each time
one of the inverter switches in the AFD is activated.
Consequently, the resonance noise frequency
corresponds to the switching frequency of the AFD.
For the VLT 8000 AQUA, Danfoss offers a LC filter
to dampen the acoustic motor noise.
This filter reduces the voltage rise time, the
peak voltage U
PEAK
and the ripple current
I to
the motor, thereby making current and voltage
almost sinusoidal. The acoustic motor noise is
therefore reduced to a minimum.
Because of the ripple current in the coils, there will be
some noise from the coils. This problem can be solved
entirely by integrating the filter in a cabinet or similar.
■
Examples of the use of LC filters
Submersible pumps
For small motors with up to and including 5.5 kW
rated motor power, use an LC filter, unless the motor
is equipped with phase separation paper. This applies
e.g. to all wet running motors. If these motors are
used without LC filter in connection with an AFD, the
motor windings will short-circuit. If in doubt, ask the
motor manufacturer whether the motor in question
is equipped with phase separation paper.
NOTE
If an AFD controls several motors in parallel,
the motor cables must be added up to
give the total cable length.
Well pumps
If immersion pumps are used, e.g. submerged pumps
or well pumps, the supplier should be contacted for
clarification of requirements. It is recommended to use
a LC filter if an AFD is used for well pump applications.
MG.80.A7.22 - VLT is a registered Danfoss trademark
17
Rosewood STP ST42 General (Operation and Maintenance Manual - Part 4:
Section 6.3 Manufacturers Manuals 6.3.33 Danfoss VLT Aquadrive 8000) Vendor Manual
QP Id: VM207
Active: 03/09/2013
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