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BETA Protecting
Residual Current Protective Devices
5
SM2 RC units, type A
2/17
Siemens ET B1 · 10/2008
2
*
You can order this quantity or a multiple thereof.
■
Overview
RC units of type A can be used in all systems up to
240/415
V AC. They trip in the event of both sinusoidal AC fault
currents and pulsating DC residual currents.
RCCBs with a rated residual current of maximum 30 mA are
used for personnel, material and fire protection, and for
additional protection against direct contact.
Devices with a rated residual current of maximum 300 mA are
used as preventative fire protection in case of insulation faults.
RC units are combined with miniature circuit breakers with
characteristics A, B, C and D, provided that these are available
in the MCB range. The two components are simply plugged
together without the need for any tools.
They then form a combination of RCCB and MCB for personnel,
fire and line protection.
Super resistant
æ
Super resistant (short-time delayed) RC units satisfy the maximum
permissible break times for instantaneous devices. However, by
implementing a short-time delay they prevent unnecessary
trippings, and thus plant faults, when pulse-shaped leakage
currents occur – as is the case when capacitors are switched on.
Selective
î
Can be used as upstream group switch for selective tripping
contrary to a downstream, instantaneous or super resistant
RCCB.
The dimensioning of the rated residual current depends on the
size of the plant.
■
Benefits
•
Our wide variety of RC unit types and comprehensive range of
miniature circuit breakers offer a huge spectrum of combinations
for all applications
•
All devices have surge current withstand capability of more
than 1 kA, thus ensuring safe and reliable operation
•
All additional components for miniature circuit breakers can
be retrofitted on the right-hand side
•
All 100 A and 125 A RC units offer external remote tripping
over terminals Y1/Y2. This supports implementation of central
OFF circuits
•
Both components can be simply plugged into each other and
secured with captive metal brackets – no tools required. This
saves considerable time when mounting.
-25
(
Type A)
© Siemens AG 2008