Siemens SIPROTEC 7SD610 Manual page 187

Address 3913 T2StartCriteria is used to set whether the delay time T2 will be started after expiry of T1
(T2StartCriteria = With exp. of T1) or simultaneously with it (T2StartCriteria = Parallel
withT1). The time T2 can also be initiated via a separate binary input 1424 „>BF STARTonlyT2".
Figure 2-75 Logic diagram of the two-stage breaker failure protection
Circuit breaker not operational
There may be cases when it is already obvious that the circuit breaker associated with a feeder protection relay
cannot clear a fault, e.g. when the tripping voltage or the tripping 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
SIPROTEC, 7SD610, Manual
C53000-G1176-C145-6, Release date 02.2011
Functions
2.13 Circuit Breaker Failure Protection
187