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multiple-phase faults. In the general settings (address 1156 Trip2phFlt, see also
Section 2.1.4.1) it can also be selected that single-pole tripping takes place for two-
phase faults without earth. Single-pole tripping is of course only possible for short-
circuit protective functions which can determine the faulty phase. The valid protection
stage selected for reclosure ready state applies to all fault types.
The automatic reclosure is started at the moment of tripping. Depending on the type
of fault, the (adjustable) dead time for the single-pole reclose cycle or the (separately
adjustable) dead time for the three-pole reclose cycle starts following the reset of the
trip command or opening of the circuit breaker (pole) (auxiliary contact criterion). After
expiry of the dead time, the circuit breaker receives a close command. At the same
time, the (adjustable) blocking time is started. If the reclosure is blocked during the
dead time following a single-pole trip, immediate three-pole tripping can take place as
an option (forced three-pole trip).
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 protec-
tion 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 dy-
namically (see also margin heading „Reclose Block", above).
The sequence above applies for single reclosure cycles. In 7SD610 multiple reclosure
(up to 8 shots) is also possible (see below).
Multiple
If a short-circuit still exists after a reclosure attempt, further reclosure attempts can be
auto-reclosure
made. Up to 8 reclosure attempts are possible with the automatic reclosure function
integrated in the 7SD610.
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) (aux-
iliary 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 permissible 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
When single-pole or single-and three-pole reclose cycles are executed in the network,
Faults
particular attention must be paid to sequential faults.
7SD610 Manual
C53000-G1176-C145-4
2.10 Automatic Reclosure Function (optional)
129
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