Lust CDA32.008 - Changing the Mains Load by Use of a Line Choke

CDA3000 Operation Manual
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A.5 Changing the
mains load by
use of a line
choke
Mains load
1) THD = Total Harmonic Distortion (voltage harmonic U5 ...U41)
Mains voltage asymmetry
Recommendation:
The example shows that the benefits of a line choke with 4 % short-circuit
voltage are multi-faceted. We therefore recommend that you use a line
choke as a matter of course.
Without line
choke
With line choke Change
4 kW inverter,
mains impedance
0.6 mH
4 kW inverter,
mains imped-
ance 6 mH
Without choke to
with choke
Voltage distortion (THD)
1)
99 % 33 % -67 %
Mains current amplitude 18,9 A 9,7 A -48 %
Mains current effective 8,5 A 6,23 A -27 %
Commutation notches
referred to mains voltage
28 V 8 V -70%
Useful life of dc link capaci-
tors
Nominal life
2 to 3 times
nominal life
+100 to 200 %
Table : Change in mains load resulting from use of a line choke with 4 % short-circuit
voltage based on the example of a 4 kW inverter CDA34.010
Without line choke With line choke
4 kW inverter, mains impe-
dance 0.6 mH
4 kW inverter, mains impe-
dance 6 mH
Asymmetry of mains
voltage
0 % +3 % -3 % 0 % +3 % -3 %
Mains current amplitude 18,9 A 25,4 A 25,1 A 9,7 A 10,7 A 11 A
Mains current effective 8,5 A 10,5 A 10,2 A 6,2 A 6,7 A 6,8 A
Table: Effect of a line choke with asymmetric mains voltage based on the
example of a 4 kW inverter CDA34.010