Siemens siprotec 7SA6 User Manual

Functions
6-2297SA6 Manual
C53000-G1176-C133-1
Figure 6-113 Current flow monitoring with the plausibility currents 3·I
0
and 3·I
2
Processing of the
Circuit Breaker
Auxiliary Contacts
The position of the circuit breaker is derived from the central function control of the
device (refer also to Section 6.20.2). Evaluation of the breaker auxiliary contacts is
carried out in the breaker failure protection function only when the current flow
monitoring has not picked up. Once the current flow criterion has picked up during the
trip signal from the feeder protection, the circuit breaker is assumed to be open as
soon as the current disappears, even if the associated auxiliary contact does not (yet)
indicate that the circuit breaker has opened (Figure 6-114). This gives preference to
the more reliable current criterion and avoids overfunctioning due to a defect e.g. in
the auxiliary contact mechanism or circuit. This interlock feature is provided for each
individual phase as well as for three-pole trip.
It is possible to disable the auxiliary contact criterion. If you set the parameter switch
&KN%5.&217$&7 (Figure 6-116 above) to 1R, the breaker failure protection can
only be started when current flow is detected. The position of the auxiliary contacts is
then not evaluated even if the auxiliary contacts are connected to the device.
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,!
,!
&
&
&
&
&
>
1
>
1
>
1
Current
criterion
I
L1
I
L2
I
L3
>
1
,!
3I
2
,!
3I
0
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L1>
L2>
L3>
plausi-
bility

Siemens siprotec 7SA6 Specifications

General

Brand	Siemens
Model	siprotec 7SA6
Category	Relays
Language	English