Datasheet

CS10.481
C-Line
48V, 5A, SINGLE PHASE INPUT
22.2. BACK-FEEDING LOADS
Loads such as decelerating motors and inductors can feed voltage back to the power supply. This feature is also called
return voltage immunity or resistance against Back- E.M.F. (Electro Magnetic Force).
This power supply is resistant and does not show malfunctioning when a load feeds back voltage to the power supply.
It does not matter whether the power supply is on or off.
The maximum allowed feed-back-voltage is 63Vdc. The absorbing energy can be calculated according to the built-in
large sized output capacitor which is specified in chapter 6.
22.3. EXTERNAL INPUT PROTECTION
The unit is tested and approved for branch circuits up to 20A. An external protection is only required if the supplying
branch has an ampacity greater than this. 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 6A C-Characteristic breaker should be used.
22.4. OUTPUT CIRCUIT BREAKERS
Standard miniature circuit breakers (MCB’s or UL 1077 circuit breakers) are commonly used for AC-supply systems and
may also be used on 48V 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 48V 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. 22-3 Test circuit
Maximal wire length
*)
for a fast (magnetic) tripping:
0.75mm² 1.0mm² 1.5mm² 2.5mm²
C-2A
59m 78m 108m 157m
C-3A
36m 48m 64m 105m
C-4A
21m 27m 38m 58m
C-6A
10m 13m 19m 28m
C-8A
4m 6m 10m 14m
C-10A
3m 4m 7m 10m
B-6A
22m 30m 42m 62m
B-10A
11m 15m 25m 26m
MCB
Power Supply
23/26
AC
DC
+
-
Load
+
-
B-13A
7m 10m 14m 18m
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).
Jul. 2015 / Rev. 2.0 DS-CS10.481-EN
All parameters are specified at 48V, 5A, 230Vac, 50Hz, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.
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