Siemens siprotec 7SD5 User Manual page 364

2 Functions
Figure 2-151 Initiation conditions with phase segregated initiation
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 2-143 or 2-144).
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
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7SD5 Manual
C53000-G1176-C169-1