Circuit Breaker Failure Protection
115
7SS52 V4 Manual
C53000-G1176-C182-3
5.3.2
(
118/CU
)
is used to set the threshold I
d
/I
n
at which the pro-
tection detects a breaker failure and/or resets a TRIP command.
Siemens recommends to set this parameter to about 50 % of the smallest short-circuit
current to be expected.
The parameter
)
is used to match the stabilizing factor for
the selective breaker failure protection and the check zone to the service conditions.
A setting value of 0.25 is recommended for the stabilization against current transform-
er errors.
This parameter is only relevant for the modes
. These modes are set with the parameter
(
XX15/CU
)
The parameter
(
XX19/CU
)
is used to set for an earth fault the threshold
I
d
/I
n
at which the protection detects a breaker failure and/or resets a TRIP.
The parameter
Is< BF.EF
(
6202A/CU
)
is used to set the stabilizing current
threshold I
s
/I
no
for the breaker failure protection in the presence of an earth fault.
The setting of the parameter depends on the maximum stabilizing current to be ex-
pected and on the behaviour of the CTs.
This parameter is only displayed if the parameter
6320A/CU
)
is set
With setting
0.00
the characteristic will not be used.
Note
Please note that the limit value
must not be set smaller than the limit value
Id>
SUPERV BZ
(
6308/CU
)
. Otherwise, there is a risk of spurious tripping if there is an
operational differential current (e.g. fault in transformer circuit) and a binary input of
the breaker failure protection is activated simultaneously.
Note
This parameter is also used for the functions “
5.4, page 135) and “
Note
This parameter is also used for the functions “
“ (Chapter
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