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2 Functions
Figure 2-72
Circuit breaker not
There may be cases when it is already obvious that the circuit breaker associated with
operational
a feeder protection relay cannot clear a fault, e.g. when the tripping voltage or the trip-
ping energy is not available.
In such a case it is not necessary to wait for the response of the feeder circuit breaker.
If provision has been made for the detection of such a condition (e.g. control voltage
monitor or air pressure monitor), the monitor alarm signal can be fed to the binary input
„>CB faulty" of the 7SD610. On occurrence of this alarm and a trip command by
the feeder protection, a separate timer T3-BkrDefective, which is normally set to
0, is started (Figure 2-73). Thus, the adjacent circuit breakers (bus-bar) are tripped im-
mediately in case the feeder circuit breaker is not operational.
Figure 2-73
Transfer trip to the
The device has the facility to provide an additional intertrip signal to the circuit breaker
remote end circuit
at the remote line end in the event that the local feeder circuit breaker fails. This re-
breaker
quires the transmission of the command.
In case of 7SD610 the corresponding command — usually the trip command which is
intended to trip the adjacent breakers — is assigned to the input function for intertrip
of the devices. This can be achieved by external wiring: The command output is con-
nected to the binary input „>Intertrip 3pol" (No. 3504) (see also Section 2.4).
186
Two-stage breaker failure protection with phase segregated initiation
Circuit breaker not operational
7SD610 Manual
C53000-G1176-C145-4
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