CPS20.241-60
C-Series
24V,
400W,
DC/DC
C
ONVERTER
Sep. 2019 / Rev. 1.1 DS-CPS20.241-60-EN
All parameters are specified at 24.5V, 16.3A, 110Vdc, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
www.pulspower.com Phone +49 89 9278 0 Germany
19/22
23.3.
E
XTERNAL
I
NPUT
P
ROTECTION
The unit is tested and approved for branch circuits up to 30A (UL) and 32A (IEC). An external protection is only
required if the supplying branch has an ampacity greater than this. Provided, that the negative pole is grounded. If the
positive pole is grounded, an additional external fast-acting input fuse in the negative input is required.
Check also local codes and local requirements. In some countries local regulations might apply.
If an external fuse is necessary or utilized, minimum requirements need to be considered to avoid nuisance tripping of
the circuit breaker. A minimum value of 10A B- or C-Characteristic breaker should be used.
23.4.
O
UTPUT
C
IRCUIT
B
REAKERS
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 DC/DC converters 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 DC/DC converter 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. 23-3
Test circuit
Maximal wire length
*)
for a fast (magnetic) tripping:
MCB
Power Supply
AC
DC
+
-
+
-
Load
Wire length
S1... Fault simulation switch
S1
0.75mm²
1.0mm²
1.5mm²
2.5mm²
C-2A
30m
40m
49m
85m
C-3A
19m
24m
35m
52m
C-4A
11m
15m
22m
31m
C-6A
4m
6m
8m
11m
C-8A
1m
1m
2m
3m
C-10A
1m
1m
2m
3m
B-6A
10m
14m
22m
34m
B-10A
3m
5m
10m
13m
B-13A
2m
4m
7m
10m
*) Don’t forget to consider twice the distance to the load (or cable length) when calculating the total wire length (+ and – wire).
23.5.
C
HARGING OF
B
ATTERIES
The DC/DC converter can not be used to charge batteries.
