Data Sheet

QS20.241, QS20.241-A1, QS20.241-C1
Q-Series
24V, 20A, SINGLE PHASE INPUT
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 30A or 32A 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. 9mA when the power supply is switched
off (except in case a blocking diode is utilized).
22.6. OUTPUT CIRCUIT BREAKERS
Standard miniature circuit breakers (MCB’s or UL1077 circuit breakers) are commonly used for AC-supply systems and
may also be used on 24V branches.
MCB’s are designed to protect wires and circuits. If the ampere value and the characteristics of the MCB are adapted to
the wire size that is used, the wiring is considered as thermally safe regardless of whether the MCB opens or not.
To avoid voltage dips and under-voltage situations in adjacent 24V branches which are supplied by the same source, a
fast (magnetic) tripping of the MCB is desired. A quick shutdown within 10ms is necessary corresponding roughly to
the ride-through time of PLC's. This requires power supplies with high current reserves and large output capacitors.
Furthermore, the impedance of the faulty branch must be sufficiently small in order for the current to actually flow.
The best current reserve in the power supply does not help if Ohm’s law does not permit current flow. The following
table has typical test results showing which B- and C-Characteristic MCBs magnetically trip depending on the wire cross
section and wire length.
Fig. 22-5 Test circuit
Maximal wire length
*)
for a fast (magnetic) tripping:
0.75mm² 1.0mm² 1.5mm² 2.5mm²
C-2A
26m 35m 62m 82m
C-3A
23m 29m 54m 72m
C-4A
15m 19m 31m 51m
C-6A
7m 10m 15m 26m
C-8A
5m 7m 10m 16m
C-10A
2m 3m 5m 7m
C-13A
- - 1m 2m
B-6A
19m 27m 38m 57m
B-10A
7m 11m 14m 23m
B-13A
1m 2m 3m 5m
MCB
Power Supply
AC
DC
+
-
+
-
Load
Wire length
S1... Fault simulation switch
S1
*) Don’t forget to consider twice the distance to the load (or cable length) when calculating the total wire length (+ and – wire).
Oct. 2013 / Rev. 2.2 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone [phone] Germany
23/26