[logik-strmflsueberw-plausibilitaet-110113, 1, en_GB]
Figure 2-33
Current flow monitoring with plausibility currents 3·Ι
0
and 3·Ι
2
1) only available/visible if 139 is set to enabled w/ 3I0>
Monitoring the circuit breaker auxiliary contacts
It is the central function control of the device that informs the circuit breaker failure protection on the position
of the circuit breaker (see Section 2.8.1 Function Control). The evaluation of the circuit breaker auxiliary
contacts is carried out in the circuit 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 protec-
tion, the circuit breaker is assumed to be open as soon as the current disappears, even if the associated auxil-
iary contact does not (yet) indicate that the circuit breaker has opened (Figure 2-34). 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 3-pole tripping.
It is possible to disable the auxiliary contact criterion. If you set the parameter switch Chk BRK CONTACT
(Figure 2-36 top) to NO the circuit 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.
Functions
2.6 Circuit breaker failure protection (optional)
SIPROTEC 4, 7VK61, Manual 117
C53000-G1176-C159-5, Edition 05.2018
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