[lo_pickdrop-210113-01.vsd, 1, en_US]
Figure 6-261 Logic Diagram for Measuring Value, Pickup/Dropout of the Circuit-Breaker Restrike Protection
If restriking occurs, the current signal drops below the current threshold if the time between restrike pulses is
long enough. In this case, the operate delay must not be reset. During the dropout delay, the pickup is
extended to ensure that the operate delay timers are not reset. However, if the dropout delay time expires (no
new current peak occurred), the function drops out and the operate delay timers are reset.
Delay/Tripping
In the first step, tripping of the local circuit breaker can be repeated. Tripping is repeated after expiration of
the settable delay T1. The retrip on the local circuit breaker is as a safety mechanism as well. In the event of a
wrong start and pickup, only the local circuit breaker is opened instead of the superordinated circuit breaker.
Time delay T2 (backup tripping) can start in parallel either with the start of time T1 or after expiration of time
T1.
If time delay T2 expires, circuit-breaker restriking takes place and the backup-tripping signal
Trip T2
is
generated.
If the
>CB defect
input signal is valid, any repetition of the trip signal is suppressed and the backup-trip-
ping signal
Trip T2
is generated immediately (without delay). For safety reasons, a default software filter
time of 20 ms is preset (configurable in DIGSI) for the binary input signal
>CB defect
.
The Minimum operate time parameter defines the minimum duration for the trip command of the func-
tion. In contrast to other protection functions, the parameter is set within its own function. As a result, the
setting is independent of the identically named comprehensive parameter that is set in the Device settings.
[lo_deltrip-030211-01.vsd, 2, en_US]
Figure 6-262 Logic Diagram for Delay/Tripping of the Circuit-Breaker Restrike Protection
Protection and Automation Functions
6.42 Circuit-Breaker Restrike Protection
856 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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