CS10.244

C-Line

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 35Vdc. The absorbing energy can be calculated according to the built-in

large sized output capacitor which is specified in chapter 6.

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 16A B- or 10A C-Characteristic breaker should be used.

Standard miniature circuit breakers (MCB’s or UL 1077 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. 22-3 Test circuit

Maximal wire length

0.75mm²

1.0mm²

1.5mm²

2.5mm²

C-2A

21m

26m

37m

68m

21/24

C-3A

15m

21m

30m

51m

MCB

Power Supply

C-4A

10m

14m

20m

38m

C-6A

4m

6m

9m

16m

C-8A

1m

2m

4m

6m

C-10A

1m

2m

3m

4m

B-6A

13m

18m

26m

42m

AC

DC

+

-

Load

+

-

Wire length

S1... Fault simulation switch

S1

B-10A

10m

5m

9m

11m

*)

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-CS10.244-EN

All parameters are specified at 24V, 10A, 230Vac, 50Hz, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

www.pulspower.com Phone +49 89 9278 0

Germany