Moeller Rapid Link, Switching And Installation System, Page: 18 / 162

System Rapid Link
01/08 AWB2190-1430GB
14
Depending on the length of the power bus and the arrangement
of the power links, the incoming circuit-breaker RA-DI can also
switch on a higher number of RA-SP units. In any case, the total
mains current of the RA-SP units must not exceed 25 A (or 20 A
at 2.5 mm
2
) in continuous operation. The mains currents
change proportionally to the currently flowing motor current.
• Observe the voltage drop in your specific application.
Instead of the disconnect control unit, you can use a 3-pole
miniature circuit-breaker
I
n
F
20 A and B or C characteristic.
Here, you must observe the following:
• The let-through energy
J
in the event of a short-circuit must
not exceed 29800 A
2
s.
• Therefore the short-circuit current
I
cc
at the mounting location
must not exceed 10 kA ( a characteristic curve figure 7).
Incoming supply 24 V DC
Use all power supply devices in combination with safe isolation
and earth them on their secondary side.
• Switched-mode power supply units with foldback characteristic
limit the short-circuit capacity by reducing the voltage and
allowing the highest permissible voltage (depending on model
rating) to flow permanently until the fault has been rectified.
Once the fault has been rectified, the voltage builds up again
(automatic restarting). This type of power supply unit must not
supply a continuous short-circuit current higher than 16 A or –
if a flat cable RA-C1-7x2,5PVC is used – 6 A.
• Switched-mode power supply units with short-circuit
recognition, i.e. with disconnection and automatic restarting,
should disconnect a short-circuit current (e.g. 3
x I
N
) after no
more than 0.1 seconds. The rated current can be up to 16 A or
– if a flat cable RA-C1-7x2,5PVC is used – 6 A.
• If non-stabilized power supply units without short-circuit
protection are used, an additional short-circuit protection
device must be fitted. In the event of a short-circuit, the
disconnection should take place after no more than 0.1
seconds. Here miniature circuit-breakers with characteristic R in
the secondary circuit are recommended. With a short-circuit
release response current of 2 – 3
x I
N
, these are suitable for the
protection of semiconductor elements . The power supply unit
must have a corresponding short-circuit capacity. The fuse
specification fo the secondary circuit must not exceed 16 A or –
if a flat cable RA-C1-7x2,5PVC is used – 6 A.
Figure 7: Cable protection with FAZ-3-B20
2 A
1 A
0.5 A
10 A
1 3 A
16 A
20 A
25 A
3 2 A
40 A
50 A
6 3 A
4 A
3 A
6 A
0.5 1.5 15 1 2 3 4 5 6 7 8 9 10
10 3
10 4
10 5
8
6
4
2
1.5
8
6
4
2
8
6
4
3
1.5
FAZ-B
FAZ-C
FAZ-...-B4HI
Z
i
2
d t
[A
2
s]
I
cc eff
[kA]
20 A
29800 A
2
s
10 kA