Danfoss AHF 010 Design Manual page 26

Requirements for Installati...
To frequency
converter
digital input
4 4
To frequency
converter
relay output
24 V DC
24 – 240 V AC
depending on
contactor type
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
Illustration 4.10. 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
Illustration 4.10) is approximately 5%, while the voltage
drop at overload (C in Illustration 4.10) is a few
percentages. Illustration 4.10 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.
24
®
VLT
X 1.1 X1.2 X1.3
27
A
AHF 1
12
B
X3. 1 X 3.2 X3.3
02
01
Danfoss A/S © 05/2019 All rights reserved.
Advanced Harmonic Filter AHF 005/AHF 010
X2.1 X2.2 X2.3
X4.1 X4.2 X4.3
DC-link voltage [%]
A
100
0
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
chapter 6 Programming.
X1.1 X1.2 X1.3 X2. 1 X2.2
A
AHF 2
B
X3.1 X3.2 X3.3 X4.1 X4.2
B
100
X2.3
X4.3
C
150/160
Load [%]
MG80C602