46
5.2.3.3
Overvoltages and surge current load
During thunderstorms, atmospheric overvoltages in the form of traveling waves
can penetrate the installation via the supply system and inadvertently trip
residual current protective devices. To prevent these spurious tripping operations,
our residual current protective devices must pass a test with the standardized
8/20 μs surge current wave (see gure 16). In the product standard EN 61008
(VDE 0664), this test is only stipulated for selective residual current protective
devices (i = 3 kA).
All versions of our Type A and B residual current operated circuit breakers offer a
signicantly higher current withstand capability. They consequently have a greatly
reduced tendency to trip falsely in practice.
The current withstand capability of the individual product series is as follows:
• instantaneous at least 1 kA
• Type F and super-resistant Type
K
at least 3 kA
• selective (Type
S
) at least 5
Even in the standard versions, these values ensure good resistance to false
tripping, and this form of protective measure with rated currents up to 30 mA can
also be used for sensitive load circuits (e.g. refrigerators).
Notes on installation and use
Figure 16: Surge current characteristic 8/20 μs
Characteristics of a current impulse
acc. to DIN VDE 0432 Part 2
T
S
Front time in s
T
r
Virtual time to half value
on tail in s
O
1
Virtual origin
I
m
Peak value
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