Functions
2.14 Automatic Reclosing System 79
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
262
Circuit Breaker Monitoring
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 impossible.
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 by an external synchronism check.
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 an external synchronism check,
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 syn-
chronism of the power systems. If synchronism prevails it switches in instantaneously, otherwise it will not.
If the synchronization is used for synchronous/asynchronous networks, the monitoring time must grant suffi-
cient 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 synchronization process (pa-
rameter 6x12).
The breaker failure monitoring time
7114
T-Start MONITOR
determines the time between tripping (closing
the trip contact) and opening the circuit breaker (checkback of the CB auxiliary contacts or disappearing device
pickup if no auxiliary contacts are allocated). This time is started each time a tripping operation takes place.
When time has elapsed, the device assumes breaker failure and blocks the auto-reclose system dynamically.
Action Time
The action time monitors the time between pickup of the device and trip command of a protective function con-
figured as starter while the automatic reclosing system is ready but not yet running. A trip command issued by
a protective function configured as starter occurring within the action time will start the automatic reclosing func-
tion. If this time differs from the setting value of
T-ACTION
(address
7117
), the automatic reclosing system will
be blocked dynamically. The trip time of inverse tripping characteristics is considerably determined by the fault
location or fault resistance. The action time prevents reclosing in case of far remote or high-resistance faults
with long tripping time. Trip commands of protective functions which are not configured as starter do not affect
the action time.
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