Siemens siprotec SJ62 User Manual page 238

Circuit Breaker
Monitoring
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
The time needed by the circuit breaker to perform a complete reclose cycle can be
monitored by the 7SJ62/63/64. Breaker failure is detected:
A precondition for a reclosing attempt, following a trip command initiated by a protec-
tive relay element and subsequent initiation of the automatic reclosing function, is that
the circuit breaker is ready for at least one TRIP-CLOSE-TRIP cycle. The readiness
of the circuit breaker is monitored by the device using a binary input „>CB Ready".
In the case where this signal from the breaker is not available, the circuit breaker mon-
itoring feature should be disabled, otherwise reclosing attempts will remain blocked.
• Especially when multiple reclosing attempts are programmed, it is a good idea to
monitor the circuit breaker condition not only prior to the first but also to each reclos-
ing attempt. A reclosing attempt will be blocked until the binary input indicates that
the circuit breaker is ready to complete another CLOSE-TRIP cycle.
• The time needed by the circuit-breaker to regain the ready state can be monitored
by the 7SJ62/63/64. The monitoring time CB TIME OUT expires for as long as the
circuit breaker does not indicate that it is ready via binary input „>CB Ready" (FNo.
2730). Meaning that as the binary input „>CB Ready" is cleared, the monitoring
time CB TIME OUT is started. If the binary input returns before the monitoring time
has elapsed, the monitoring time will be cancelled and the reclosure process is con-
tinued. If the monitoring time runs longer than the dead time, the dead time will be
extended accordingly. If the monitoring time elapses before the circuit breaker
signals its readiness, the automatic reclosure function will be blocked dynamically.
Interaction with the synchronism check may cause the dead time to extend inadmissi-
bly. To prevent the automatic reclosure function from remaining in an undefined state,
dead time extension is monitored. The maximum extension of the dead time can be
set at Max. DEAD EXT.. The monitoring time Max. DEAD EXT. is started when the
regular dead time has elapsed. If the synchronism check responds before the time has
elapsed, the monitoring time will be stopped and the close command generated. If the
time expires before the synchronism check reacts, the automatic reclosure function
will be blocked dynamically.
Please make sure that the above mentioned time is not shorter than the monitoring
time CB TIME OUT.
The time 7114 T-Start MONITOR serves for monitoring the response of the auto-
matic reclosure function to a breaker failure. It is activated by a trip command arriving
before or during a reclosing operation and marks the time that passes between trip-
ping and opening of the circuit breaker. If the time elapses, the device assumes a
breaker failure and the automatic reclosure function is blocked dynamically. If param-
eter T-Start MONITOR is set to ∞, the start monitoring is disabled.
2.14 Automatic Reclosing System 79
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