Siemens siprotec 7SA6 User Manual page 590

Circuit Breaker
Auxiliary Contacts
External Start
Conditions
Due to the variety of application options and the available system
configurations, it is not possible to make a detailed description of the
necessary tests. It is important to consider the local conditions and the
protection and plant drawings.
It is advised to isolate the circuit breaker of the tested feeder at both
sides, i.e. to keep the busbar isolator and the line isolator open, in order
to ensure operation of the breaker without risk.
Caution!
Also for tests on the local circuit breaker of the feeder a trip command to the surround-
ing circuit breakers can be issued for the busbar. Therefore the tripping of the sur-
rounding circuit breakers (busbar) must be deactivated, e. g. by switching off the cor-
responding control voltages.Nevertheless ensure that trip remains possible in case of
a real primary fault if parts of the power plant are in service.
The trip command of the tested Distance Protection is made ineffective
so that the local breaker can be tripped only by the breaker failure
protection function of 7SA6.
Although the following lists do not claim to be complete it may also
contain points which are to be ignored in the current application.
If the circuit breaker auxiliary contacts are connected to the device, these
provide an essential input to the functionality of the breaker failure
protection. Make sure the correct assignment has been checked (Section
8.3.3).
If the breaker failure protection can also be started by external protection
devices, the external start conditions should be checked. Single-pole or
three-pole tripping is possible depending on the setting of the breaker
failure protection. The pole discrepancy check of the device or the
breaker may itself lead to three-pole tripping after single-pole tripping.
Therefore check first how the parameters of the breaker failure protection
are set. See Subsection 6.16.2, addresses   onwards.
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.
After every start, the message "%) 6WDUW" (FNo. ) must appear in
the spontaneous annunciation list or the trip log.
Only if phase segregated starting possible:
q
single-pole starting by trip command of the external protection in
phase L1:
binary input functions "!%) 6WDUW /" and possibly "!%) UHOHDVH"
(in spontaneous or fault messages). Trip command depending on
configuration.
q
single-pole starting by trip command of the external protection in
phase L2:
7SA6 Manual
C53000-G1176-C133-1