Siemens SIRIUS 3RH Series, System Manual

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SIRIUS 3RV2 motor starter protectors
4.5 Configuration
SIRIUS Innovations
394
System Manual, 01/2011, A8E56203870002-03
4.5.9 Switching direct current
3RV2 motor starter protectors for AC current are also suitable for switching direct current.
When used for this purpose, however, the maximum permissible DC voltage per current path
must be observed. With higher voltages, series connection of 2 or 3 current paths is
required.
Response values
The response values of the overload releases remain unchanged, while the response values
of the short-circuit releases increase by up to 40% with a DC current. The following table
contains suggested circuits for switching direct current:
Table 4- 4 Switching direct current, suggested circuits
Suggested circuit Motor starter
protector
Size Max. permissible
direct voltage U
e
Meaning
0
/ /
3RV2. S00/S0 150 V DC 2-pole switching, non-grounded
system (see also Note)
If there is no possibility of a
ground fault occurring, or if any
ground fault which does occur is
dealt with immediately (ground-
fault monitoring), then the max.
permissible direct voltage can be
tripled.
0
/ /
3RV2. S00/S0 300 V DC 2-pole switching, grounded
system
The grounded pole always has to
be assigned to the individual
current path, so that in the event
of a ground fault there are always
2 current paths in series.
0
/ /
3RV2. S00/S0 450 V DC 1-pole switching, grounded
system
3 current paths in series The
grounded pole has to be assigned
to the current path which is not
connected.
Note
Double ground fault
In the case of the "2-pole switching, non-grounded system" circuit, it is assumed that safe
tripping will follow even in the event of a double ground fault which short-circuits two
contacts.