Data Sheet

QT20.241, QT20.241-C1
Q-Series
24V, 20A, THREE PHASE INPUT
Apr. 2017 / Rev. 2.1 DS-QT20.241-EN
22.4. USING ONLY 2 LEGS OF A 3-PHASE SYSTEM
No external protection devices are required to protect against a phase-loss
failure.
DC
L1
L2
L3
open
AC
L1
L2
L3
PE
Power Supply
This power supply can also be permanently operated on two legs of a 3-
phase system. However, it is not recommended for this power class since the
supplying 3-phase network can become unbalanced.
The output power must be reduced according to the curves below when
operation on only two legs of a 3-phase system. A long-term exceeding of
these limits will result in a thermal shut-down of the unit.
EMC performance, hold-up time, losses and output ripple differ from a three phase operation. Therefore, check
suitability of your individual application.
Such use is not included in the UL approval. Additional tests might be necessary when the complete system has to be
approved according to UL 508 or UL60950-1.
Fig. 22-5
Output current vs. ambient temperature -
2-phase operation
Fig. 22-6
Hold-up time – 2-phase operation
Allowed Output Current at 24V
23/27
0
-25 0 20
70°C
5
10
15
20
25
30A
c
o
n
t
i
n
u
o
u
s
f
o
r
t
y
p
.
4
s
40 60
A
.
.
.
2
x
4
6
0
t
o
5
5
2
V
a
c
B
.
.
.
2
x
3
4
0
t
o
4
6
0
V
a
c
B
A
Ambient Temperature
0
10
20
30
320 360 400 440 2x480Vac
40
50ms
Hold-up Time for Use on only Two Legs of a
Three Phase System
2
4
V,
1
0
A
,
t
y
p
.
2
4
V,
1
0
A
,
m
i
n
.
2
4
V
,
2
0
A
,
t
y
p
.
2
4
V
,
2
0
A
,
m
i
n
.
Input Voltage
22.5. CHARGING OF BATTERIES
The power supply can be used to charge lead-acid or maintenance free batteries. (Two 12V batteries in series)
Instructions for charging batteries:
a) Set output voltage (measured at no load and at the battery end of the cable) very precisely to the end-of-charge
voltage.
End-of-charge voltage 27.8V 27.5V 27.15V 26.8V
Battery temperature 10°C 20°C 30°C 40°C
b) Use a 25A circuit breaker (or blocking diode) between the power supply and the battery.
c) Ensure that the output current of the power supply is below the allowed charging current of the battery.
d) Use only matched batteries when putting 12V types in series.
e) The return current to the power supply (battery discharge current) is typ. 16mA when the power supply is
switched off (except in case a blocking diode is utilized).
All parameters are typical values specified at 24V, 20A, 3x 400Vac, 50Hz, symmetrical mains voltages, 25°C ambient and after
a 5 minutes run-in time unless otherwise noted.
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