2.18 Circuit breaker failure protection (optional)
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7SA522 Manual
C53000-G1176-C155-3
The additional release-signal ´!%)UHOHDVHµ (if assigned to a binary input) affects
all starting conditions. Initiation can be blocked via the binary input ´!%/2&.
%NU)DLOµ (e.g. during test of the feeder protection relay). Additionally, an internal
blocking option is provided.
Figure 2-128 Initiation conditions with single-pole trip command
Delay Times When the initiate conditions are fulfilled, the associated timers are started. The circuit
breaker pole(s) must open before the associated time has elapsed.
Different delay timers are provided for operation after common phase initiation and
phase segregated initiation. A third time stage can be used for two-stage breaker
failure protection.
With single-stage breaker failure protection
, the trip command is routed to the adjacent
circuit breakers should the local feeder breaker fail (refer to Figure 2-120 or 2-121).
The adjacent circuit breakers are those which must trip in order to interrupt the fault
current, i.e. the breakers which feed the busbar or the busbar section to which the
feeder under consideration is connected. The possible initiation conditions for the
breaker failure protection are those discussed above. Depending on the application of
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