24 V DC
24 – 240 V AC
X 1.1 X1.2 X1.3 X2.1 X2.2 X2.3
X3.1 X 3.2 X3.3 X4.1 X4.2 X4.3
AHF 1
X1.1 X1.2 X1.3 X2.1 X2.2 X2.3
X3.1 X3.2 X3.3 X4.1 X4.2 X4.3
AHF 2
To frequency
converter
relay output
01
02
depending on
contactor type
A
B
A
B
To frequency
converter
digital input
12
27
130BB638.1
1
Illustration 4.9 Parallel Use of AHF Combined with Capacitor Disconnect
NOTICE
It is not allowed to use 1 common 3-poled contactor
with paralleled filters.
NOTICE
Keep the cable length between the filter and the
capacitor disconnect contactor as short as possible to
reduce the impedance influence on the cable. A
maximum cable length of 2 m (6.6 ft) is allowed between
filter and contactor.
Voltage boost
The AHF is designed to ensure the lowest possible
insertion loss to provide full DC-link voltage in the
frequency converter. The target of this design is to ensure
full DC-link voltage at nominal load, see B in
. Providing the full DC-link voltage at
nominal load results in a minor voltage boost at low-load
conditions and a minor voltage drop at overload
conditions. The voltage boost at low load (A in
) is approximately 5%, while the voltage
drop at overload (C in
) is a few
percentages.
shows the insertion loss in the
frequency converter as a function of load.
NOTICE
The voltage boost causes the voltage at the frequency
converter terminals to be up to 5% higher than the
voltage at the input of the filter when the capacitors are
not disconnected. Consider this situation when designing
the installation. Take special care in 690 V applications
where the voltage tolerance of the frequency converter
is reduced to +5%, unless a capacitor disconnect is used.
DC-link voltage [%]
100
100
Load [%]
130BE888.10
A
C
B
0
150/160
A
Low-load condition or standby. Approximately 5%
voltage boost occurs without the capacitors being
disconnected. If the capacitors are disconnected, the
voltage boost can be reduced.
B
Nominal load condition. The AHF is optimized for full
DC-link voltage in the frequency converter at nominal
load conditions.
C
Overload condition. A voltage drop of a few
percentages occurs at high overload conditions.
Illustration 4.10 Insertion Loss in the Frequency Converter as a
Function of Load
NOTICE
Only switch the contactor at less than 20% output
power. Allow minimum 25 s for the capacitors to
discharge before reconnecting. See more details in
.
Requirements for Installati...
VLT
®
Advanced Harmonic Filter AHF 005/AHF 010
24
Danfoss A/S © 05/2019 All rights reserved.
MG80C602
4
4
Summary of Contents for AHF 010
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