Part - Leutron GmbH

Power Engineering
Class I+II (T1+T2) Combined Arresters
Only the first protection stage responds during occurring
transient surges of low energy. The main spark gap will not
fire. Due to the limiting behaviour of the MOV varistor the response
of the first protection stage will not result in a short
circuit and, therefore, in no follow-on short-circuit current.
The back-up fuse will not actuate in this case.
The main spark gap extinguishes follow-on short-circuit currents
only under certain conditions. If a maximum operational
availability is desired, a back-up fuse of ≤ 160 A is necessary
to extinguish a firing main spark gap and, thus, preventing
it from thermal damage. In most cases a back-up fuse will
be installed in industrial applications and for maintenance
reasons, whereby the power supply will not be interrupted
even if the SPD fails.
Lightning impulse currents with a high energy content cause
the main spark gap to fire immediately after the triggering
of the first protection stage. Hence, the main spark gap with
its discharge capacity unloads the first stage and protects it
against damage.
With back-up fuses or circuit-breakers of more than 160 A a
selective back-up fuse (fusible cutout) of a maximum of 160 A
has to be installed to avoid an overload of the IsoPro caused
by a high short-circuit current.
In 230 V ac networks the optional potential-free remote contact
(FM) can be updated by an additional acoustic/optical
signalling device UAS 230-Tr with test key (Item no. 35 10 30),
even at a later point in time.
Combined modular arresters of the series BC offer a higher
insulation level and lower investment and installation costs,
due to their low residual voltage. They are able to divert high
lightning impulse currents and operate also at small, transient
surges under different ambient conditions without any additional
trigger – reliably and without any problems.
Leutron GmbH · Humboldtstrasse 30 · 70771 Leinfelden-Echterdingen · Germany · Phone +49 711 94771-0 · www.leutron.de
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