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If the fault is cleared (successful reclosure), the reclaim time expires and all functions return to their quiescent
state. The fault is cleared.
If the fault has not been eliminated (unsuccessful reclosure), the short-circuit protection initiates a final three-
pole trip with the protection stage valid without reclosure. Any fault during the blocking time leads to a final
three-pole trip.
After unsuccessful reclosure (final tripping), the automatic reclosure is blocked dynamically (see also margin
heading „Reclose Block", above).
The sequence above applies for single reclosure cycles. In 7VK61 multiple reclosure (up to 8 shots) is also
possible (see below).
Multiple auto-reclosure
If a short-circuit still exists after a reclosure attempt, further reclosure attempts can be made. Up to 8 reclosure
attempts are possible with the automatic reclosure function integrated in the 7VK61.
The first four reclose cycles are independent of each other. Each one has separate action and dead times, can
operate with single- or three-pole trip and can be blocked separately via binary inputs. The parameters and
intervention possibilities of the fourth cycle also apply to the fifth cycle and onwards.
The sequence is the same in principle as in the different reclosure programs described above. However, if the
first reclosure attempt was unsuccessful, the reclosure function is not blocked, but instead the next reclose
cycle is started. The appropriate dead time starts with the reset of the trip command or opening of the circuit
breaker (pole) (auxiliary contact criterion). The circuit breaker receives a new close command after expiry of
the dead time. At the same time the reclaim time is started.
Until the set maximum number of permissible auto-reclose cycles has been reached, the reclaim time is reset
with every new trip command after reclosure and started again with the next close command.
If one of the reclosing attempts is successful, i.e. the fault disappeared after reclosure, the blocking time expires
and the automatic reclosing system is reset. The fault is cleared.
If none of the cycles is successful, the short-circuit protection initiates a final three-pole trip after the last per-
missible reclosure, following a protection stage valid without auto-reclosure. The automatic reclosure function
is blocked dynamically (see also margin heading „Blocking reclosure", above).
Handling Evolving Faults
When single-pole or single-and three-pole reclose cycles are executed in the network, particular attention must
be paid to sequential faults.
Sequential faults are faults which occur during the dead time after clearance of the first fault.
There are various ways of handling sequential faults in the 7VK61 depending on the requirements of the net-
work:
For the Detection of an evolving fault you can select whether the trip command of a protective function during
the dead time or every further pickup is the criterion for an evolving fault.
SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009
2.2 Automatic reclosure function (optional)
Functions
49
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