Siemens SIPROTEC 4 7SD80 Manual page 99

transmission). With devices using digital transmission via protection interface, the remote commands can be
applied (see also Section
To realize this intertrip, the desired command – usually the trip command which is intended to trip the adja-
cent breakers — is assigned to a binary output of the device. The contact of this output triggers the transmis-
sion device. When using digital signal transmission the command is connected to a remote command via the
userdefined logic (CFC).
End Fault Protection
An end fault is defined here as a fault which has occurred at the end of a line or protected object, between the
circuit breaker and the current transformer set.
This situation is shown in
ment location) — on the busbar side, it will thus not be regarded as a feeder fault by the feeder protection
device. It can only be detected by either a reverse element of the feeder protection or by the busbar protec-
tion. However, a trip command given to the feeder circuit breaker does not clear the fault since the opposite
end continues to feed the fault. Thus, the fault current does not stop flowing even though the feeder circuit
breaker has properly responded to the trip command.
[endfehler-ls-strwdlr-wlk-010802, 1, en_US]
Figure 2-41
The end fault protection has the task to recognize this situation and to transmit a trip signal to the remote
end(s) of the protected object to clear the fault. For this purpose, the output command
available to trigger a signal transmission device (e.g. power line carrier, radio wave, or optical fiber) – if appli-
cable, together with other commands that need to be transferred or (when using digital signal transmission)
as command via the protection data interface.
The end fault protection detects an end fault because it registers that current is flowing even though the
circuitbreaker auxiliary contacts signal that the circuit breaker is open. An additional criterion is the presence
of any breaker failure protection initiate signal.
failure protection is initiated and current flow is detected (current criteria "L*> current criterion" according to
Figure 2-36), but no circuit-breaker pole is closed (auxiliary contact criterion "52 closed"), the timer EndFault
Delay is started. At the end of this time, a trip command is sent to the opposite end.
[lo-svs-endfehler-20101112, 1, en_US]
Figure 2-42
SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018
2.13 Direct Remote Trip and Transmission of Binary
Figure 2-41. The fault is located — as seen from the current transformer (= measure-
End fault between circuit breaker and current transformers
Functional diagram of the end fault protection
2.6 Circuit Breaker Failure Protection 50BF
Figure 2-42 shows the functional principle. If the breaker
Functions
Information).
50BF EndFltTrip is
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