Siemens SIPROTEC 7SJ61, Руководство пользователя, Страница: 174 / 454

Functions
2.11 Automatic Reclosing System 79
SIPROTEC, 7SJ61, Manual
C53000-G1140-C210-1, Release date 02.2008
174
A longer restraint time should be chosen if there is no possibility to monitor the circuit breaker (see below)
during multiple reclosing (e.g. because of missing auxiliary contacts and and information on the circuit breaker
ready status). In this case, the restraint time should be longer than the time required for the circuit breaker
mechanism to be ready.
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 functional description gives further information on this
topic, see marginal heading "Dynamic Blocking". The dynamic blocking is associated with the configurable
blocking time
SAFETY 79 ready
. Dynamic blocking time is usually started by a blocking condition that has
picked up.
Circuit Breaker Monitoring
Reclosing after a fault tripping 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 a synchronization function (internal or external),
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 external 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 subnet-
works. A monitoring time of 100 s should be sufficient to account for most applications for asynchronous net-
works.
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.