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BETA Protecting
Miniature Circuit Breakers
Configuration
1/86
Siemens ET B1 · 10/2008
1
*
You can order this quantity or a multiple thereof.
Voltage-independent main miniature circuit breakers (SHU)
Selective main miniature circuit breakers are generally based on
the miniature circuit principle of operation of conventional miniature
circuit breakers and have a delayed thermal release for overload
protection and an electromagnetic fast release with an impact
cutout blade for short-circuit protection.
An additional selectivity device is also used that recognizes
whether the downstream miniature circuit breaker in the load cir-
cuit is capable of dealing with the short circuit on its own. If it de-
tects that this will exceed the capacity of the miniature circuit
breaker, the selective main miniature circuit breaker will trip.
Regardless of the rated current of the selective main miniature
circuit breaker, this ensures a selectivity for downstreamminiature
circuit breakers according to IEC/EN 60898, DIN VDE 0641-11,
up to its rated switching capacity.
Furthermore, the selective main miniature circuit breaker also
offers a back-up protection of up to 25 kA to all downstream
miniature circuit breakers.
Application examples
Full selectivity up to the rated switching capacity of the down-
stream miniature circuit breaker.
Selectivity towards upstream fuses up to 2000 A
I2_06718c
230
V
SHU
MCB
S
*
E 25
B 16
NH
40
gl
I2_06719c
230
V
SHU
MCB
S
*
© Siemens AG 2008