Functions
170
7SS52 V4 Manual
C53000-G1176-C182-3
5.9.5
Feeder-Selective Trip Release
The 7SS52 provides the possibility, in the event of a busbar short-circuit, to trip only
those feeders for which an additional external criterion is fulfilled. Such a TRIP com-
mand release can be provided, for instance, by a pickup of the feeder protection.
The TRIP release must be marshalled to a binary output “
>TRIP release
”
(
FNo. 7616/BU
)
in the bay unit.
In the event of a busbar TRIP the breaker failure protection time delay (CBF time de-
lay) is started. If TRIP release is not given within the CBF time delay, no trip command
is generated and the status”missing TRIP release” is indicated for the feeder con-
cerned.
The missing”TRIP release” does not influence the internal CBF processing.
5.9.6
Testing the Tripping Circuits and the Circuit Breakers
You can test the tripping circuits and the circuit breakers under live conditions by initi-
ating a CB test trip from the bay unit. The CB test live trip can be performed with DIGSI
or directly from the bay unit operator panel.
The following conditions must be met:
•
The required test trip commands have been marshalled to the trip relays during con-
figuration.
•
The feeder current must not exceed the threshold set in
6316/CU
).
As Figure 5-38, page 170 shows, the circuit breaker test live trip can be initiated from
the bay unit by one of the following:
•
Pressing function key
F2
(3-phase),
•
via binary input”
>CB Test
” (
FNo. 1156/BU
) (3-phase),
•
with the parameter
CB TEST LIVE TRIP
(
4400/BU
) (1-/3-phase).
The CB test trip command is cancelled after a fixed time of 2 s.
Figure 5-38 CB test live trip function
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