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
Battery temperature
27.8V
10°C
27.5V
20°C
27.15V
30°C
26.8V
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
26m
23m
15m
7m
1.0mm²
35m
29m
19m
10m
7m
1.5mm²
62m
54m
31m
15m
10m
5m
2.5mm²
82m
72m
51m
26m
16m
7m
C-2A
C-3A
MCB
Power Supply
Load
C-4A
+
C-6A
+
AC
C-8A
5m
Wire length
S1
C-10A
C-13A
B-6A
2m
3m
-
-
DC
-
-
1m
2m
S1... Fault simulation switch
19m
7m
27m
11m
2m
38m
14m
3m
57m
23m
5m
B-10A
B-13A
1m
*) 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.
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PULS [ PULS GmbH ]
