Functions
2.17 Automatic Reclosure Function (optional)
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
335
2.17.2 Setting Notes
General
If no reclosure is required on the feeder to which the 7SD5 line protection is applied (e.g. for cables, transform-
ers), the auto reclose function must be disabled during configuration of the device (address 133, see also
Section 2.1.1.3). The auto reclose function is then fully disabled, i.e. the automatic reclosure is not processed
in the 7SD5. No signals regarding the auto reclose function are generated, and the binary inputs for the auto
reclose function are ignored. All parameters for setting the automatic reclosure function are inaccessible and
of no significance.
But if the internal automatic reclosure function is to be used, the type of reclosure must be selected during the
configuration of the device functions (see Section 2.1.1.3) in address 133 Auto Reclose and in address 134
the AR control mode.
Up to 8 reclosure attempts are allowed with the integrated automatic reclosure function in the 7SD5. Whereas
the settings in address 3401 to 3441 are common to all reclosure cycles, the individual settings of the cycles
are made from address 3450 onwards. It is possible to set different individual parameters for the first four
reclose cycles. From the fifth cycle on the parameters for the fourth cycle apply.
The automatic reclosing function can be turned ON or OFF under address 3401 AUTO RECLOSE.
A prerequisite for automatic reclosure taking place after a trip due to a short-circuit is that the circuit breaker is
ready for at least one OPEN-CLOSE-OPEN cycle at the time the automatic reclosure circuit is started, i.e. at
the time of the first trip command. The readiness of the circuit breaker is signalled to the device via the binary
input „>CB1 Ready“ (No. 371). If no such signal is available, leave the setting under address 3402 CB?
1.TRIP = NO because no automatic reclosure would be possible at all otherwise. If circuit breaker interrogation
is possible, you should set CB? 1.TRIP = YES.
Furthermore, the circuit breaker ready state can also be interrogated prior to every reclosure. This is set when
setting the individual reclose cycles (see below).
To check that the ready status of the circuit breaker is regained during the dead times, you can set a circuit
breaker ready monitoring time under address 3409 CB TIME OUT. The time is set slightly longer than the re-
covery time of the circuit breaker after an OPEN-CLOSE-OPEN cycle. If the circuit breaker is not ready again
by the time this timer expires, no reclosure takes place and the automatic reclosure function is blocked dynam-
ically.
Waiting for the circuit breaker to be ready can cause an increase of the dead times. Interrogation of a synchro-
nism check (if used) can also delay reclosure. To avoid uncontrolled prolongation, it is possible to set a
maximum prolongation of the dead time in this case in address 3411 T-DEAD EXT.
. This prolongation is un-
limited if the setting ∞ is applied. This parameter can only be altered in DIGSI at Display Additional Settings.
Remember that longer dead times are only permissible after 3-pole tripping when no stability problems occur
or a synchronism check takes place before reclosure.
T-RECLAIM (address 3403) is the time after which the fault is considered eliminated following successful
re-
closure. If a protection function provokes a new trip before this time has elapsed, the next reclosing cycle is
started in case of multiple reclosure. If no further reclosing attempt is allowed, the last reclosure will be consid-
ered failed in the event of a new trip. The reclaim time must therefore be longer than the longest response time
of a protection function which can start the automatic reclosure function. When operating the AR in ADT mode,
it is possible to deactivate the reclaim time by setting it to 0 s.
A few seconds are generally sufficient. In areas with frequent thunderstorms or storms, a shorter blocking time
may be necessary to avoid feeder lockout due to sequential lightning strikes or cable flashovers.
A longer reclaim time should be chosen where circuit breaker supervision is not possible (see above) during
multiple reclosures, e.g. because of missing auxiliary contacts and information on the circuit breaker ready
status. In this case, the reclaim time should be longer than the time required for the circuit breaker mechanism
to be ready.
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