Brochure/Catalogue

General installation advice
Fuse protection
Surge protection devices for instrumentation and control
systems frequently operate with a decoupling between the
components. This decoupling is carried out using inductors
or resistors. The decoupling dictates the cable type, cable
routing and also a fusing for the maximum nominal current
of the surge protection devices. The fusing for the VPU series
on the power supply side must be installed in accordance
with DIN VDE 0298 part 4 (cross section, quantity, type of
conductor and the type of installation). This information is
documented in the package insert and on the products for
the corresponding VPU modules. In the event of overloads
caused by partial lightning currents or transformer short
circuits, the lightning arrester and surge arrester (SPD) must
be protected by a back-up fuse if F1 is greater than the value
specied by the manufacturer. In compliance with the ratio
1:1.6, the maximum nominal value should be congured for
the SPD. Depending on the installation of the connecting
cables, F1 can be increased during the lifespan of the facility.
If a circuit breaker or a main circuit breaker is used instead of
the safety fuse required in the installation instructions, then
the triggering characteristics must be followed.
An equivalent main circuit breaker (MCB) can be used
instead of the fuse.
In normative terms, however, a test is only carried out in
combination with the SPD and the fuse.
Lightning current strength of NH fuses
for surge currents 10/350 μs
50
10
1
I
limit
in kA
Lightning surge current
10/350 µs
- - - - -
Values from the
1-ms melting integral
10 35 63 100 160 250
Fuse nominal currents in A
15.6…29.8 kA
13.2…16.4 kA
6.8…10.3 kA
4.4…6.1 kA
2.3…3.7 kA
Lightning current strength of NH fuses
for surge currents 8/20 μs
60
50
40
30
20
10
0
I
max
in kA
Lightning surge current
820 µs
- - - - -
Values from the
1-ms melting integral
0 10 35 50 63 100 150 160 200
Fuse nominal currents in A
43…55 kA
28…34 kA
18…24 kA
12…14 kA
2.7…4.3 kA
W
The basics of lightning and surge protection
W.192028840000