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Figure 6-254 Pickup/Dropout of the Circuit-Breaker Failure Protection Function
Delay/Tripping
In a first step, tripping at the local circuit breaker can be repeated. Tripping is repeated after expiration of the
settable delay T1. If the local CB was not yet tripped, for example, in the event of an external start of the
circuit-breaker failure protection, the trip logic of the circuit breaker itself is activated when the time delay T1
elapses.
Time delay T2 (backup tripping) can commence in parallel either with the start of time T1 or after expiration of
time T1.
If time delay T2 expires without a dropout of the function, a circuit-breaker failure is assumed and the backup
tripping signal Tripping T2 is output. If there is a protection interface in the device, if needed a transfer-trip
signal can be sent to the opposite end.
You can find detailed information in the chapter 3.5.3 Protection Interface and Protection Topology.
If the >CB defect input signal is valid, any repetition of the trip signal is suppressed, and the backup tripping
signal T2 is generated immediately (without delay). The binary input of the >CB defect input signal must be
activated for at least 20 ms before the signal becomes valid.
With help of the
CB failure pole
indication, you can determine the phase currents that are above the
threshold value at the tripping time T2.
The Minimum operate time parameter defines the minimum duration for tripping the function. In contrast
to other protection functions, the parameter is set within its own function. As a result, the setting is inde-
pendent of the identically named global parameter that is set in the Device settings.
Protection and Automation Functions
6.41 Circuit-Breaker Failure Protection
842 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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