Table 2-4: Suggestions For Switching Direct Current - Siemens sirius System Manual

3RV1 circuit breakers
Parallel cables/meshed
networks
2.3.6 Switching direct current
Response thresholds
Suggestion
L + L -
M
+
L L -
M
+
L L-
M

Table 2-4: Suggestions for switching direct current

Double ground fault
2-16
Attention
In the case of parallel cables and meshed networks, a tripping operation and
report only occurs when the voltage difference at the circuit breaker is at
least 24 V.
The 3RV1 circuit breakers for alternating current are suitable for switching
direct current. However, you must note the maximum permissible DC volt-
age per conducting path. In the case of higher voltages, series connection
of 2 or 3 conducting paths is required.
The response thresholds of the overload releases remain unchanged. The
response thresholds of the short-circuit releases are increased with direct
current by approximately 40%.
The following table lists suggestions for switching direct current:
Circuit Frame
breaker size
3RV1. S00 to
S3
3RV1. S00 to
S3
3RV1. S00 to
S3
Note
In the case of the circuit with 2-pole switching and an ungrounded system, it
is assumed that even in the event of a double ground fault that bridges two
contacts, safe disconnection still occurs.
Max.
permissible Meaning
direct voltage
E
I
150 VDC 2-pole switching
Ungrounded system
If a ground fault can be excluded, or if every
ground fault is immediately corrected
(ground-fault monitoring), the maximum per-
missible DC voltage can be tripled.
300 VDC 2-pole switching
Grounded system
The grounded pole must always be assigned
to the individual conducting path so that in
the event of a ground fault there are always
2 conducting paths in series.
450 VDC 1-pole switching
Grounded system
3 conducting paths in series.
The grounded pole should be assigned to
the unswitched conducting path.
SIRIUS System Manual
GWA 4NEB 430 0999-02b