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BETA Protecting
Residual Current Protective Devices
5
SU1 RCBOs, type A
2/30
Siemens ET B1 · 10/2008
2
*
You can order this quantity or a multiple thereof.
■
More information
Selectivity of RCBOs/fuses
Distribution systems are usually set up as radial networks. An
overcurrent protection device is required for each reduction of
the conductor cross-section. This produces a series connection
staggered according to rated currents, which should be "selective"
if possible.
Selectivity means that, in the event of a fault, only the protective
device that is directly next to the fault in the current path is
tripped. This means that parallel current paths can maintain a
power flow.
In the case of RCBOs with upstream fuses, the selectivity
limit depends largely on the current limitation and tripping
characteristics of the RCBO and the melting
I
2
t value of the fuse.
This produces different selectivity limits for RCBOs with different
characteristics and rated switching capacity.
The following tables provide information on the short-circuit currents
up to which selectivity exists between RCBOs and upstream
fuse according to DIN VDE 0636 Part 21. The values specified in
kA are limit values that were determined under unfavorable test
conditions. Under normal practical conditions, you can often
expect considerably better values, depending on the upstream
fuses.
Limit values of selectivity of RCBOs/fuses in kA
Downstream RCBOs
Upstream fuses
I
n
[
A]
16
A
20
A
25
A
35
A
50
A
63
A
80
A
100
A 125 A
Characteristic B 5SU1 .56
6
0.4
0.7
1.1
2.0
4.1
•
•
•
--
10
--
0.5
0.75
1.4
2.4
3.4
4.2
•
--
13
--
0.45
0.7
1.3
2.0
2.7
3.6
•
--
16
--
0.45
0.7
1.3
2.0
2.7
3.6
•
--
20
--
--
0.7
1.3
2.0
2.7
3.6
•
--
25
--
--
--
1.3
2.0
2.7
3.6
•
--
32
--
--
--
--
2.0
2.7
3.6
•
--
40
--
--
--
--
1.8
2.7
3.6
•
--
Characteristic C 5SU1 .56
6
0.35
0.55
0.8
1.5
2.8
4.7
•
•
--
8
--
0.45
0.7
1.4
2.3
3.3
4.2
•
--
10
--
0.45
0.7
1.4
2.3
3.3
4.2
•
--
13
--
0.4
0.6
1.2
2.0
3.0
3.5
•
--
16
--
0.4
0.6
1.2
2.0
3.0
3.5
•
--
20
--
--
0.6
1.2
2.0
3.0
3.5
•
--
25
--
--
--
1.2
2.0
3.0
3.5
•
--
32
--
--
--
--
2.0
2.8
3.5
•
--
40
--
--
--
--
1.8
2.8
3.5
•
--
•
r
rated switching capacity according to EN 61009-1
.
Characteristic B 5SU1 .54
6
0.45
0.7
1.1
2.2
5.0
•
•
10
--
0.55
0.8
1.5
2.8
4.6
7.0
•
•
13
--
0.5
0.75
1.4
2.3
3.9
6.0
•
•
16
--
0.5
0.75
1.4
2.3
3.9
6.0
•
•
20
--
--
0.75
1.4
2.3
3.9
6.0
•
•
25
--
--
--
1.2
2.0
3.1
4.5
8.0
•
32
--
--
--
--
2.0
3.1
4.5
8.0
•
40
--
--
--
--
1.8
2.8
4.0
7.0
•
Characteristic C 5SU1 .54
6
0.4
0.6
0.9
1.7
3.3
6.5
•
•
•
8
--
0.5
0.8
1.5
2.7
5.0
7.0
•
•
10
--
0.5
0.8
1.5
2.7
5.0
7.0
•
•
13
--
0.5
0.7
1.3
2.3
4.0
5.0
•
•
16
--
0.5
0.7
1.3
2.3
4.0
5.0
•
•
20
--
--
0.6
1.2
2.0
3.2
4.4
8.0
•
25
--
--
--
1.2
2.0
3.2
4.4
8.0
•
32
--
--
--
--
1.8
2.8
3.6
7.0
•
40
--
--
--
--
1.8
2.8
3.6
7.0
•
•
r
rated switching capacity according to EN 61009-1
.
6 000
10 000
© Siemens AG 2008