Functions
6-258
7SA6 Manual
C53000-G1176-C156-2
End Fault
Protection
An end fault is defined here as a short–circuit 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 Figure 6-133. The fault is located — as seen from the current
transformers (= measurement location) — on the bus-bar side, thus, it will not be re-
garded by the feeder protection relay as a feeder fault. It can only be detected by either
a reverse stage of the feeder protection or by a bus-bar protection. Nevertheless, a
trip command given to the feeder circuit breaker cannot clear the fault since the oppo-
site end(s) continue(s) 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.
Figure 6-133 End fault between circuit breaker and current transformers
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 “
BF EndFlt TRIP
” is available to trigger a signal transmission
device (e.g. power line carrier, radio wave, or optical fibre) — if applicable, together
with other commands that need to be transferred.
The end fault is recognized when the current continues flowing although the circuit
breaker auxiliary contacts indicate that the breaker is open. In the 7SA6, an additional
criterion is the presence of any breaker failure protection initiate signal. The scheme
functionality is shown in Figure 6-134. If the breaker failure protection is initiated and
current flow is recognized (current criteria “L
∗
>” according Figure 6-122), but no circuit
breaker pole is closed (auxiliary contact criterion “CB any pole closed”), then a timer
T-EndFault
is started, after which an intertrip signal is transmitted to the opposite
end(s) of the protected object.
Figure 6-134 Function block diagram of end fault protection
Bus-bar
Trip by
protection
Feeder
I
SC
&
3922
T-ENDFault
BF EndFlt TRIP
CB any pole closed
> 1
L2>
L3>
L1>
&
T
BF Start
(f
ro
m
F
ig
6-
12
2
)
FNo 1495
FNo 1461
0
Summary of Contents for siprotec 7SA6
Page 2: ...Siemens Aktiengesellschaft Book No C53000 G1176 C156 2 ...
Page 18: ...xviii 7SA6 Manual C53000 G1176 C156 2 ...
Page 32: ...Introduction 1 14 7SA6 Manual C53000 G1176 C156 2 ...
Page 82: ...Hardware and Connections 2 50 7SA6 Manual C53000 G1176 C156 2 ...
Page 119: ...SIPROTEC 4 Devices 4 25 7SA6 Manual C53000 G1176 C156 2 Figure 4 20 CFC Logic example ...
Page 190: ...Configuration 5 62 7SA6 Manual C53000 G1176 C156 2 ...
Page 652: ...Installation and Commissioning 8 78 7SA6 Manual C53000 G1176 C156 2 ...
Page 724: ...Technical Data 10 56 7SA6 Manual C53000 G1176 C156 ...
Page 800: ...Appendix A 76 7SA6 Manual C53000 G1176 C156 2 ...
Page 866: ...Appendix B 66 7SA6 Manual C53000 G1176 C156 2 ...