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Functions
2.6 Circuit Breaker Failure Protection 50BF
[logik-strmflsueberw-plausibilitaet-wlk-010802, 1, en_US]
Figure 2-36
1)
only usable/visible if address 139 is set to vorh. mit 3I0>
In-Phase Start
Common phase initiation is used for transformer feeders or if the busbar protection trips.
If the breaker failure protection is intended to be initiated by further external protection devices, it is recom-
mended, for security reasons, to connect two starting criteria to the device. Besides the trip command of the
external relay to the binary input
general device pickup to binary input
mended that the trip command is connected to the device by two separate wire pairs.
Nevertheless, it is possible to initiate the breaker failure protection in single-channel mode should a separate
release criterion not be available. The binary input
to any physical input of the device during configuration.
Figure 2-38
shows the operating principle. When the trip signal appears from any internal or external feeder
protection and at least one current flow criterion (according to
protection is initiated and the corresponding time delay(s) is (are) started.
If the current criterion is not satisfied for any of the phases, the circuit-breaker auxiliary contact can be interro-
gated according to
when no current flows over any of the poles.
96
Current flow monitoring with plausibility currents 3·Ι
>50BF Start 3p (FNo. 1415) it is recommended to connect also the
>50BF release (FNo. 1432). For Buchholz protection it is recom-
Figure
2-37. After a 3-pole trip command, the circuit breaker has only operated correctly
and 3·Ι
0
2
>50BF release (FNo. 1432) must then not be assigned
Figure
2-36) is present, the breaker failure
E50417-G1100-C474-A2, Edition 02.2018
SIPROTEC 4, 7SD80, Manual
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