Siemens Sivacon S8, Planning Information, Page: 85 / 112

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SIVACON S8 Planning Principles – Conforming to standards and design-verified
The arcing concept of SIVACON S8
Siemens has developed a graded concept which comprises
the requirements of arc resistance SIVACON S8 may be
subjected to. The arc levels (Tab. 9/3) describe the limita-
tion of effects of an internal arc on the system or system
components of the SIVACON S8.
System characteristics under arcing conditions
The following data must be provided by the assembly
manufacturer:
• Rated operating voltage
U
e
• Permissible short-circuit current under arcing conditions
I
p arc
and the associated permissible arcing time t
arc
or
• Permissible conditional short-circuit current under arcing
conditions I
pc arc
Corresponding characteristics for SIVACON S8 are given in
Tab. 9/2.
In addition, to include system protection, the defined areas
(e.g. cubicle, compartment) must be given to which the
effects of the internal arc shall be limited. The properties of
current-limiting devices (e.g. current-limiting circuit-break-
ers or fuses) which are required for circuit protection must
be specified if applicable.
Assessment criteria for personal safety and system
protection
Personal safety is ensured if the following five criteria are
fulfilled:
1. Properly secured doors, covers, etc., must not open.
2. Parts (of the assembly) that are potentially hazardous
must not fly off.
3. The impact of an internal arc must not produce any holes
in the freely accessible outer parts of the enclosure as a
result of burning or other effects.
4. Vertically applied indicators must not ignite.
5. The PE circuit for parts of the enclosure that can be
touched must still be functional.
System protection is ensured if the five above-mentioned
criteria are fulfilled plus criterion 6.
6. The internal arc must be limited to a defined area and
there will be no re-ignition in adjacent areas.
Suitability for restricted continued service (additional
criterion 7):
7. Emergency operation of the assembly must be possible
after the fault has been rectified and affected functional
units were disconnected or removed. This must be verified
by an insulation test with 1.5 times the value of the rated
operating voltage for the duration of one minute.
Tab. 9/2: SIVACON S8 system characteristics under arcing
conditions
Rated operating voltage U
e
Up to 690 V
Prospective short-circuit current under arcing
conditions
I
p,arc
Up to 100 kA
Arcing time t
arc
Up to 300 ms
Tab. 9/3: SIVACON S8 arc levels (system areas to which the internal
arc is limited are marked in orange)
Level 1
Personal safety
without extensive
limitation of the
arcing fault effects
within the
installation.
Level 3
Personal safety with
limitation of the arcing
fault effects to the
main busbar compart-
ment , to the device
compartment or to the
cable compartment in
one cubicle or
double-front unit.
Level 4
Personal safety
with limitation of
the arcing fault
effects to the place
of origin.
Level 2
Personal safety
with limitation of the
arcing fault effects to
one cubicle or
double-front unit.