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Functions
2.2 Automatic reclosure function (optional)
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 monitor time under address 3409 CB TIME OUT. The time is set slightly longer than the recovery
time of the circuit breaker after a TRIP-CLOSE-TRIP cycle. If the circuit breaker is not ready again by the time
this timer expires, no reclosure takes place, the automatic reclosure function is blocked dynamically.
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 three-pole tripping when no stability problems
occur or a synchronism check takes place before reclosure.
The reclaim time T-RECLAIM (address 3403) defines the time that must elapse, after a successful reclosing
attempt, before the auto reclose function is reset. Re-tripping by a protective function within this time initiates
the next reclose cycle in the event of multiple reclosure; if no further reclosure is permitted, the last reclosure
is treated as unsuccessful. The reclaim time must therefore be longer than the longest response time of a pro-
tective function which can start the automatic reclosure circuit. When operating the AR in ADT mode, it is pos-
sible 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.
The blocking duration following manual-close detection T-BLOCK MC (address 3404) must ensure the circuit
breaker to open and close reliably (0.5 s to 1 s). If a fault is detected by a protective function within this time
after closing of the circuit breaker was detected, no reclosure takes place and a final three-pole trip command
is issued. If this is not desired, address 3404 is set to 0.
The options for handling evolving faults are described in Section 2.2 under margin heading „Handling Evolving
Faults". The treatment of sequential faults is not necessary on line ends where the adaptive dead time is
applied (address 133 Auto Reclose = ADT). The addresses 3406 and 3407 are then of no consequence
and therefore not accessible.
The detection of an evolving fault can be defined under address 3406 EV. FLT. RECOG..EV. FLT. RECOG.
with PICKUP means that, during a dead time, every pickup of a protective function will be interpreted as an
evolving fault. With EV. FLT. RECOG. with TRIP a fault during a dead time is only interpreted as a evolving
fault if it has led to a trip command by a protection function. The evolving fault detection with pickup presup-
poses that a pickup signal of the external device is also connected to the 7VK61; otherwise an evolving fault
can only be detected with the external trip command even if with PICKUP was set here.
The reaction in response to sequential faults can be selected at address 3407. EV. FLT. MODE blocks AR
means that no reclosure is performed after detection of a sequential fault. This is always useful when only
single-pole reclosure is to take place or when stability problems are expected due to the subsequent three-pole
dead time. If a three-pole reclose cycle is to be initiated by tripping of the sequential fault, set EV. FLT. MODE
= starts 3p AR. In this case a separately adjustable three-pole dead time is started with the three-pole trip
command due to the sequential fault. This is only useful if three-pole reclosure is also permitted.
56
SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009
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