Parameter: Monit. time for BI ">Start"/Monit.tm. f.BI ">Release"
•
Default setting (_:124) Monit. time for BI ">Start" = 15 s
•
Default setting (_:125) Monit.tm. f.BI ">Release" = 15 s
With these parameters, you set the monitoring time of the binary inputs >Start/>Release. If the Circuit-
breaker failure protection does not pick up during this monitoring time, a failure in the binary-input circuit is
assumed. Siemens recommends retaining the default setting of 15 s.
EXAMPLES
Applications which require you to permit the circuit-breaker auxiliary contact criterion:
•
Tripping of the high and low-voltage side CB on the transformer. If only one of the 2 CBs trips, there is no
more current flow.
•
Tripping of protection functions whose tripping decision is not based on current measurement in combi-
nation with voltage or frequency protection functions
•
Injection of the tripping signal from Buchholz protection
Parameter: Dropout
•
Recommended setting value (_:104) Dropout = with effective criterion
The parameter Dropout is available if the circuit-breaker auxiliary contact criterion is permitted (see param-
eter CB aux.cont. crit. allowed).
Parameter Value
Description
with effective crite-
rion
Siemens recommends keeping the default setting, because it prefers the
current as a reliable criterion for detection of an open CB and thus for
dropout of the CBFP function.
w. aux.c. and
curr.crit.
Select this setting for applications on transformers or generators (see the
preceding examples) in which the current flow is such that the current is no
longer a reliable criterion for detecting the opening of the CB.
Parameter: Retrip
•
Default setting (_:108) Retrip after T1 = no
Parameter Value
Description
no
Where no redundant CB control is provided, a repetition of the trip signal to
the local CB is not required.
start T2 after T1
Where a redundant CB control (2nd trip coil with 2 trip circuits) is provided,
a repetition of the trip signal to the local CB makes sense.
Siemens recommends the setting start T2 after T1 because it
provides a clear chronological separation of the processes for trip repeat
and backup tripping. Remember here that the overall fault-clearance time in
case of a failure of the local CB is the sum of T1 and T2.
parallel start T2, T1
As an alternative to the setting start T2 after T1, the user can start T2
and T1 in parallel.
Parameter: Delay T1 for 3-pole retrip
•
Default setting (_:109) Delay T1 for 3-pole retrip = 0.05 s
The parameter is visible only when retripping is set.
The setting depends on the user's philosophy.
The following settings make sense:
Protection and Automation Functions
6.41 Circuit-Breaker Failure Protection
848 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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