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BETA Protecting
SITOR Semiconductor Fuses
SITOR, LV HRC design
4/3
Siemens ET B1 · 10/2008
4
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Overview
SITOR fuses protect power semiconductors from the effects of a
short circuit because the super-quick disconnect characteristic
is far quicker than that of conventional LV HRC fuses. They
protect expensive devices and system components such as
converters with fuses in the input and in the DC link, UPS systems
and soft starters for motors.
Panel mounting requirements have given rise to various connection
versions and designs.
The fuses with blade contacts comply with IEC 60269-2 and are
suitable for installation in LV HRC fuse bases, in LV HRC switch
disconnectors and in switch disconnectors with fuses. They also
include fuses with slotted blade contacts for screw fixing with
110
mm mounting dimension, whose sizes comply with
IEC 60269-4.
Fuses with slotted blade contacts for screw fixing with 80 mm or
110
mm mounting dimension are often screwed directly onto
busbars for optimum heat dissipation. Even better heat
transmission is provided by the compact fuses with M10 or M12
female thread, which are also mounted directly onto busbars.
Bolt-on links with 80 mm mounting dimension are another
panel-mounting version for direct busbar mounting.
The fuses for SITOR thyristor sets, railway rectifiers or electrolysis
systems were developed specially for these applications.
To find out which LV HRC fuse bases and safety switching
devices can be used with the SITOR fuses, please refer to the
chapter "Low-voltage fuse systems".
The characteristic curves for the configuration and assignment
of SITOR fuses to fuse bases and 3NP and 3KL safety switching
devices can be found in the Catalog ET B1 Add-On Characteristic
Curves and on the Internet.
The new size 3 type ranges have a round ceramic body instead
of a square one. Key features of these type ranges are small
I
²
t
values with low power dissipation and a high alternating load
capability. The dimensions and the functional dimensions
comply with the current standards IEC 60269-4/EN 60269-4
(
VDE 0636-4).
Note:
The ordering data of the fuses are listed in ascending order of
the rated voltage in the selection tables.
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Benefits
•
SITOR fuses have a high varying load factor, which ensures a
high level of operating safety and plant availability – even
when subject to constant load change.
•
The use of SITOR fuses in LV HRC bases or Siemens switch
disconnectors has been tested with regard to heat dissipation
and maximum current loading. This makes planning and
dimensioning easier and prevents consequential damage.
•
Our high standard of quality ensures good compliance with
the characteristic curve and accuracy. This ensures long-term
protection of devices.
Operational classes
Fuses are categorized according to function and operational
classes. SITOR semiconductor fuses, in LV HRC design, are
available in the following operational classes:
•
aR: for the short-circuit protection of power semiconductors
(
partial range protection)
•
gR: for the protection of power semiconductors
(
full range protection)
•
gS: The gS operational class combines cable and line protection
with semiconductor protection (full range protection).
© Siemens AG 2008