Operating instructions7SV512
V1
C53000---G1176---C91
76
fault inception
fault clearance time normal
prot.
trip
initiation breaker failure
protection
time delay T1 of breaker failure
protection
CB operating time
(adjacent CBs)
total fault clearance time with breaker failure
trip command
repeat
safety
margin
reset
I---BF
CB operating time
(local)
safety
margin
reset
I---BF
time delay T2 of breaker
failure protection
Figure 6.3 Time sequence example for normal clearance of a fault, and with circuit breaker failure, using
two-stage breaker failure protection
fault inception
fault clearance time normal
prot. reset safety
trip CB operating time I---BF margin
initiation breaker failure
protection
time delay T2 of CB operating time
breaker failure protection (adjacent CBs)
total fault clearance time with breaker failure
Figure 6.2 Time sequence example for normal clearance of a fault, and with circuit breaker failure, using
single-stage breaker failure protection
Ifthe circuit breaker associated with the feeder isnot
operative (e.g. control voltage failure or air pressure
failure), it is clear that the breaker cannon clear the
fault. Time delay fortripping theadjacent breakers is
not necessary in this case. If the relay is informed
about this disturbance (via the binary input ”>CB
defect”,the adjacent circuit breakers (bus-bar and
remote end if applicable) are tripped after the time
T3CB---DEF (address 1214)which isnormally set to
0.
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