Functions
122
7SS52 V4 Manual
C53000-G1176-C182-3
The circuit breaker failure protection (CBF) function is initiated by the TRIP command
from the feeder protection.
is set with the parameter
(
XX15/CU
),
the feeder current is monitored for exceeding the threshold set with the parameter
(
XX18/CU
(
XX19/CU
A feeder current above this threshold starts the delay time set with the parameter
(
X X20/CU
(
XX21/CU
).
If the feeder current is still above the threshold after this delay has elapsed, the central
unit issues a 3-pole TRIP command to isolate the bus zone. In the case of a circuit
breaker failure (internal BF), the alarms "
Trip Lx CZ
" (
FNo. 10457/CU, 10458/
CU, 10459/CU
), "
Trip BF G
"
(
10436/CU
), "
Device trip G
"
(
FNo. 10445/
CU)
"
Fault rec. run."
(
FNo. 30053/CU),
"
Trip BF $03 Lx
"
(
177.1352.$03/CU, 177.1353.$03/CU, 177.1354.$03/CU
), "
Trip $03 G
"
(
177.1341.$03/CU
), "Tri
p Lx G
" (
FNo. 10446/CU, 10447/CU, 10448/CU
),
"
TrnsfTrip $00
"
(
176.1082.$00/CU
) and the group alarm "
Transf. Trip G"
(
10433/CU
) will be issued.
is set with the parameter
(
XX15/CU
), the current is monitored for exceeding the threshold set with the parame-
XX18/CU
) or
XX19/CU
). A current above this threshold starts
the delay time for the TRIP repetition, which is set with the parameter
(
XX25/CU
).
If this release criterion is fulfilled for all of the delay time for the TRIP repetition, the
bay unit issues a 1-pole or 3-pole TRIP command to the local circuit breaker.
A single-pole TRIP repetition is generated on condition that the feeder current in the
CBF-initiating phase and at least one of the other currents (phase or ground current)
exceed the adjustable threshold (ILx & IE) set with the parameter
I> BF
(
XX18/CU
)
or
I> BF-EF
(
XX19/CU
). For this purpose, set the parameter
(
XX17/CU
. The TRIP repetition is always three-polar if the feeder current
exceeds in at least 2 phases the value set with the parameters
I> BF
(
XX18/CU
) or
I> BF-EF
(
XX19/CU
).
If the circuit breaker trips correctly, the initiation and thus the CBF function is cleared.
If the CBF initiation persists, the time delay of the CBF - set with the parameter
(
XX20/CU
) or
XX21/CU
) - elapses. In conformity with the current isola-
tor replica, all feeders are tripped which are allocated to the bus zone of the CBF ini-
tiating bay unit.
A further condition is that the current threshold, which can be set individually for each
feeder with the parameter
XX18/CU
), is exceeded during the total time period.
www
. ElectricalPartManuals
. com