Part - Leutron GmbH

Power Engineering
Class I (T1) Lightning Current Arresters
IsoPro B, 2-pole
• All-in-one modular protection unit, ready for connection
• Discharge capacity up to 100 kA (10/350µs)
• Maximum operational availability
• Rare-gas-filled spark gap, hermetically sealed
• Operates independently of atmospheric air pressure
and ambient humidity
• Protection level = 4 kV
• V-wiring with multi-functional terminals
• High TOV resistance
• High insulation resistance
• No blow-out vents, thus, not requiring any safety
clearance to other installations
• No leakage currents, thus, allowing installation
upstream of power meters
• Optional remote signalling contact (FM) requiring no
additional space
Two-pole lightning current arresters for the protection of
low-voltage consumers’ installations in industry, business and
residential areas against transient surges caused by switching
actions or lightning.
The arresters can be installed at the transition 0 A to 1 according
to the lightning protection zones concept.
The single-phase (2-pole) IsoPro series is subdivided into the
following performance groups and voltage protection levels:
• 25 kA and 60 kA (10/350 µs) per active conductor or, at TT
systems, between N and PE 100 kA (10/350 µs), and between
the active conductors and PE or N, therefore in total:
50 kA or 100 kA.
• It is classified as class I (T1) SPD (former category B) with
a voltage protection level of 4 kV depending on the impulse
current load.
The series IsoPro (IP) is based on a well-proved technology.
Per pole two selectively responding protection stages are
placed in a combined DIN housing (2 MW of only 35 mm). The
leakage current-free protective circuit consists of a varistor
(MOV) and a gas-filled surge arrester (GDT) connected in series.
In addition, a rare-gas-filled, hermetically sealed highperformance
isolating spark gap from industrial ceramics
– resistant against pressure and high temperatures – is connected
in parallel.
Therefore, the SPDs of the series IsoPro can confidentially
be applied at all protection levels according to DIN EN 62305
(VDE 0185-305).
This SPD has a redundant function. In case of a (theoretically
possible) malfunction of the first protection stage the robust
and overload-resistant main spark gap remains in operation
and guarantees the coarse protection of the network.
In case of high-energy lightning impulse currents the main
spark gap fires, thus, protecting the first protection stage
(MOV and GDT) against thermal overload.
Due to the application of the gas discharge technology in
both protection stages, the IsoPro SPDs are resistant against
temporary and long lasting overvoltages (TOV) up to 500 V
(50 Hz).
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.
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.
Leutron GmbH · Humboldtstrasse 30 · 70771 Leinfelden-Echterdingen · Germany · Phone +49 711 94771-0 · www.leutron.de
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