Figure 2-37 shows the generation of the internal signal “52 closed” (see Figure 2-38 left) if at least one breaker
pole is closed.
Using binary input 1424
>50BFSTRTonlyT2
, the trip time delay 3906 50BF-2 Delay can be started. After it
has elapsed, the breaker failure protection TRIP command 1494
50BF BusTrip
is generated.
[lo-svs-signal-hiko-20101108, 1, en_US]
Figure 2-37 Generation of the signal "CB aux closed"
If an internal protection function or an external protection device trips without current flow, the breaker
failure protection is initiated by the internal input “Start internal w/o I”, if the trip signal comes from the
internal voltage protection or frequency protection, or by the external input
>50BF STARTw/oI
. In this case
the start signal is maintained until the circuit breaker is signaled to be open by the auxiliary contact criterion.
Initiation can be blocked via the binary input
>BLOCK 50BF
(e.g. during test of the feeder protection relay).
[lo-svs-phasengem-anwurf-20101108, 1, en_US]
Figure 2-38 Circuit-breaker failure protection with common phase initiation
Time Delays
When the initiate conditions are fulfilled, the associated timers are started. The circuit-breaker pole(s) must
open before the associated time has elapsed.
Time delays can be set for 3-pole initiation and for two-element protection.
With
single-element breaker failure protection, the trip command is relayed to the adjacent circuit breakers
which interrupt the fault current if the local feeder breaker fails (see Figure 2-34 and Figure 2-35). The adja-
cent circuit breakers are those located at the busbar or busbar section to which the feeder under consideration
Functions
2.6 Circuit Breaker Failure Protection 50BF
SIPROTEC 4, 7SD80, Manual 97
E50417-G1100-C474-A2, Edition 02.2018
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