Siemens siprotec SJ62 User Manual page 243

2 Functions
Circuit Breaker
Monitoring
241
If a dynamic blocking of the automatic reclosing system was initiated, then reclosing
functions remain blocked until the cause of the blocking has been cleared. The func-
tional description gives further information on this topic, see marginal heading "Dy-
namic Blocking". The dynamic blocking is associated with the configurable blocking
time SAFETY 79 ready. Dynamic blocking time is usually started by a blocking con-
dition that has picked up.
Reclosing after a fault clearance presupposes that the circuit breaker is ready for at
least one TRIP-CLOSE-TRIP cycle at the time when the reclosing function is initiated
(i.e. at the beginning of a trip command):
The readiness of the circuit breaker is monitored by the device using a binary input
„>CB Ready" (FNo. 2730).
• It is possible to check the status of the circuit breaker before each reclosure or to
disable this option (address 7113, CHECK CB?):
CHECK CB? = No check, deactivates the circuit breaker check,
CHECK CB? = Chk each cycle, to verify the circuit breaker status before each
reclosing command.
Checking the status of the circuit breaker is usually recommended. Should the
breaker not provide such a signal, you can disable the circuit breaker check at
address 7113 CHECK CB? (No check), as otherwise auto-reclosure would be im-
possible.
The status monitoring time CB TIME OUT can be configured at address 7115 if the
circuit breaker check was enabled at address 7113. This time is set slightly higher
than the maximum recovery time of the circuit breaker following reclosure. If the
circuit breaker is not ready after the time has expired, reclosing is omitted and
dynamic blocking is initiated. Automatic reclosure thus is blocked.
Time Max. DEAD EXT. serves for monitoring the dead time extension. The extension
can be initiated by the circuit breaker monitoring time CB TIME OUT and the synchro-
nization function.
The monitoring time Max. DEAD EXT. is started after the configured dead time has
elapsed.
This time must not be shorter than CB TIME OUT. When using the monitoring time CB
TIME OUT, the time Max. DEAD EXT. should be set to a value ≥ CB TIME OUT.
If the auto-reclose system is operated with a synchronization function (internal or ex-
ternal), Max. DEAD EXT. assures that the auto-reclose system does not remain in
undefined state when the synchronism check fails to check back.
If the synchronization is used as synchronism check (for synchronous systems), the
monitoring time may be configured quite short, e.g. to some seconds. In this case the
synchronizing function merely checks the synchronism of the power systems. If syn-
chronism prevails it switches in instantaneously, otherwise it will not.
If the synchronization is used for synchronous/asynchronous networks, the monitoring
time must grant sufficient time for determining the time for switching in. This depends
on the frequency slip of the two subnetworks. A monitoring time of 100 s should be
sufficient to account for most applications for asynchronous networks.
Generally, the monitoring time should be longer than the maximum duration of the syn-
chronization process (parameter 6x12).
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015