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BETA Protecting
Residual Current Protective Devices
Residual-current operated circuit breakers
2/40
Siemens ET B1 · 10/2008
2
*
You can order this quantity or a multiple thereof.
Surge current withstand capability
During thunderstorms, atmospheric overvoltages in the form of
traveling waves can penetrate the installations of a system over
an overhead system and trip the residual current protective
devices.
To prevent such inadvertent tripping operations, residual current
protective devices sensitive to power pulse currents must pass
specific tests proving its surge current withstand capability.
These tests are carried out using a surge current of the
standardized surge current wave 8/20 s.
Surge current wave 8/20 s (front time 8 s: time to half-value 20 s)
Siemens residual current protective devices of types A and B all
have a high surge current withstand capability. The following table
shows the surge current withstand capability of the various
versions:
Switching capacity, short-circuit strength
In accordance with the installation regulations DIN VDE 0100-410
(
protection against electric shock) residual current protective
devices can be installed in three system types (TN, TT and
IT systems).
However, if using the neutral conductor as a protection conductor
in TN systems, a fault may cause residual currents similar to a
short-circuit. For this reason, residual current protective devices
must be installed together with a back-up fuse and have the
appropriate short-circuit strength. Tests have been defined for
this purpose.
The short-circuit strength of the combination must be specified
on the devices.
Siemens residual current protective devices, together with a
suitable back-up fuse, have a short-circuit strength of 10 000 A.
This is the highest possible level of short-circuit strength as
specified in the VDE regulations.
Data for the rated switching capacity according to IEC/EN 61008,
i.e. the maximum permissible short-circuit back-up fuses for
residual current protective devices are contained in the following
table:
Example:
Short-circuit strength 10 kA with max. permissible short-circuit
back-up fuse 100 A.
Version
Surge current withstand
capability
Instantaneous
> 1 kA
Short-time delayed,
super resistant
æ
> 3 kA
Selective
î
> 5 kA
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Rated current of the
residual current
protective device
Rated switching
capacity
I
m
acc. to
IEC/EN 61008
(
VDE 0664) with a
grid distance of
35
mm
Maximum permissible
short-circuit back-up
fuse, LV HRC, DIAZED,
NEOZED operational
class gL/gG for residual
current protective
device
125 ...
400
V AC
500
V AC
A
A
A
A
Type A
16 ... 40
2
MW 500
63
--
63
2.5
MW 800
100
--
80
2.5
MW 800
100
--
100
2
MW 1000
125
--
125
2
MW 1250
125
--
25 ... 63
4
MW 800
100
63
80
4
MW 800
100
--
100
4
MW 1000
125
--
125
4
MW 1250
125
--
Type B
25 ... 80
4
MW 800
100
--
© Siemens AG 2008