Danfoss VLT AHF 005

3.1.2 Capacitive Currents
If the specic application requires a higher power factor at
no-load and a reduction of the capacitive current in
standby, use a capacitor disconnect. A contactor
disconnects the capacitor at loads below 20%.
NOTICE
It is important to note that the capacitors must not be
connected at full load or disconnected at no load.
It is important to consider the capacitive current in the
design of applications where the harmonic lter is supplied
by a generator. The capacitive current can cause
overvoltage of the generator in no-load and low-load
conditions. The overvoltage causes an increase of the
voltage, which then may exceed the allowed voltage for
the lter and the frequency converter. Therefore, always
use a capacitor disconnect in generator applications and
consider the design carefully. For more information about
capacitive currents, refer to chapter 4.2.1.1 Terminals for
Capacitor Disconnect.
Compared to multi-pulse rectiers, passive harmonic lters
(such as VLT
®
Advanced Harmonic Filter AHF 005/AHF 010)
are more robust against background distortion and supply
imbalance. However, the performance of passive lters is
inferior to the performance of active lters when it comes
to part load performance and power factor. For details
about the performance positioning of the various
harmonic mitigation solutions oered by Danfoss, consult
the relevant harmonic mitigation manuals.
3.2 Energy Eciency
3.2.1 Introduction to Energy Eciency
The standard EN 50598 Ecodesign for power drive systems,
motor starters, power electronics, and their driven
applications provides guidelines for assessing the energy
eciency of frequency converters.
The standard provides a neutral method for determining
eciency classes and power losses at full load and at part
load. The standard allows combination of any motor with
any frequency converter.
Extended product
Motor system
Drive system (PDS)
Complete drive module (CDM)
Infeed
section
Auxiliaries Auxiliaries Motor
Motor starter
contactors, soft starters, ...
Motor control system = CDM or starter
Driven equipment
Trans-
mission
Load
machine
Basic
drive
module
(BDM)
Mains
and
mains
cable
130BE604.11
Illustration 3.9 Power Drive System (PDS) and Complete Drive Module (CDM)
Auxiliaries:
•
VLT
®
Advanced Harmonic Filter AHF 005
•
VLT
®
Advanced Harmonic Filter AHF 010
•
VLT
®
Line Reactor MCC 103
•
VLT
®
Sine-wave Filter MCC 101
•
VLT
®
dU/dt Filter MCC 102
Basic Operating Principle o...
VLT
®
Advanced Harmonic Filter AHF 005/AHF 010
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