Rockwell Automation 1606-XLS240E, -XLS240EA, -XLS240EC, -XLS240E-D Power Supply Reference Manual - Manual (Page 23)

All parameters are specified at 24V, 10A, 230Vac, 25°C ambient and after a 5 minutes run-in time, unless noted otherwise.
Rockwell Automation Publication 1606-RM044A-EN-P — March 2014 23
Bulletin 1606 Switched Mode Power Supplies
23.5. Charging 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 15A or 16A 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. 3mA when the power supply is switched
off (except if using a blocking diode).
23.6. Output Circuit Breakers
Standard miniature circuit breakers (MCBs or UL1077 circuit breakers) are commonly used for AC-supply systems and
may also be used on 24V branches.
MCBs 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 PLCs. 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. 23-5 Test circuit Maximal wire length *) for a fast (magnetic) tripping:
0.75mm² 1.0mm² 1.5mm² 2.5mm²
C-2A 23m 29m 48m 69m
C-3A 20m 24m 38m 57m
C-4A 12m 16m 22m 33m
C-6A 5m 7m 9m 14m
C-8A 3m 4m 5m 7m
C-10A 2m 3m 4m 6m
C-13A 1m 1m 2m 2m
B-6A 11m 14m 24m 34m
B-10A 5m 8m 11m 18m
MCB Power Supply
AC
DC
+
-
Load
+
-
B-13A 4m 6m 8m 10m
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).