that the measured currents for breaker failure protection (CTs), the tested circuit breaker, and its auxiliary
contact( s) relate to the same measuring location or side of the protected object.
External Initiation Conditions
If the breaker failure protection is intended to be initiated by external protection devices, each of the external
initiation conditions must be checked.
In order for the breaker failure protection to be started, a current must flow at least via the monitored phase.
This may be a secondary injected current.
•
Start by trip command of the external protection: binary input
>BrkFail extSRC
(No 047.2651) in
spontaneous or fault annunciations.
•
Following initiation the annunciation
BkrFail ext PU
(No 047.2653) must appear in the fault annun-
ciations (trip log) or in the spontaneous annunciations.
•
With two-stage breaker failure protection, the trip repetition command to the local circuit breaker is
issued after the delay time T1 (address 7015), and the indication
BF T1-TRIP(loc)
(No 047.2654).
•
With single- or two-stage failure protection, the trip repetition command to the local circuit breaker is
issued after the delay time T2 (address 7016), and the indication
BF T2-TRIP(bus)
(No 047.2655)
Switch off test current.
If start is possible without current flow:
•
Close tested circuit breaker while the disconnectors at both sides are open.
•
Start by trip command of the external protection:
Binary input
>BrkFail extSRC
(No 047.2651) in the spontaneous or fault annunciations.
•
Following initiation the annunciation
BkrFail ext PU
(No 047.2653) must appear in the fault annun-
ciations (trip log) or in the spontaneous annunciations.
•
With two-stage breaker failure protection, the trip repetition command to the local circuit breaker is
issued after the delay time T1 (address 7015), and the indication
BF T1-TRIP(loc)
(No 047.2654).
•
With single- or two-stage failure protection, the trip repetition command to the local circuit breaker is
issued after the delay time T2 (address 7016), and the indication
BF T2-TRIP(bus)
(No 047.2655).
Reopen the local circuit breaker.
Busbar Trip
The most important thing is the check of the correct distribution of the trip commands to the adjacent circuit
breakers in case of breaker failure.
The adjacent circuit breakers are those of all feeders which must be tripped in order to ensure interruption of
the fault current should the local breaker fail. In other words, the adjacent breakers are those of all feeders
which may feed the same busbar or busbar section as the faulty feeder. In case of a power transformer, the
adjacent breakers may include the breaker of the lower-voltage side (or any other side) of the transformer, if
the upper voltage side breaker is to be monitored, and vice versa.
A general detailed test guide cannot be specified because the layout of the adjacent circuit breakers largely
depends on the system topology.
In particular with multiple busbars the trip distribution logic for the surrounding circuit breakers must be
checked. Here check for every busbar section that all circuit breakers which are connected to the same busbar
section as the feeder circuit breaker under observation are tripped, and no other breakers.
Termination of the Checks
All temporary measures taken for testing must be undone. This is to ensure that all switching devices of the
system are in the correct state, that interrupted trigger connections are restored and that control voltages are
activated. Setting values that may have been changed for the tests, must be corrected and protective func-
tions that were switched, must be set to the intended switching state (ON or OFF).
Mounting and Commissioning
3.3 Commissioning
SIPROTEC 4, 7UT6x, Manual 371
C53000-G1176-C230-5, Edition 09.2016
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