2 Functions
126
7SD610 Manual
C53000-G1176-C145-4
Blocking reclosure Different conditions lead to blocking of the automatic reclosure. No reclosure is possi-
ble, for example, if it is blocked via a binary input. If the automatic reclosure has not
yet been started, it cannot be started at all. If a reclosure cycle is already in progress,
dynamic blocking takes place (see below).
Each individual cycle may also be blocked via binary input. In this case the cycle con-
cerned is declared as invalid and will be skipped in the sequence of permissible
cycles. If blocking takes place while the cycle concerned is already running, this leads
to aborting of the reclosure, i.e. no reclosure takes place even if other valid cycles
have been parameterized.
Internal blocking signals, with a limited duration, arise during the course of the reclose
cycles:
The blocking time T-RECLAIM (address 3403) is started with each automatic reclo-
sure command. The only exception is the ADT mode where the blocking time can be
disabled by setting it to 0 s. If the reclosure is successful, all functions of the automatic
reclosure return to the idle state at the end of the blocking time; a fault after expiry of
the blocking time is treated as a new fault in the power system. If the blocking time is
disabled in ADT mode, each new trip after reclosing is considered as a new fault. If
one of the protective functions causes another trip during the blocking time, the next
reclosure cycle will be started if multiple reclosure has been set. If no further reclosure
attempts are permitted, the last reclosure is regarded as unsuccessful in case of
another trip during the blocking time. The automatic reclosure is blocked dynamically.
The dynamic lock-out locks the reclosure for the duration of the dynamic lock-out time
(0.5 s). This occurs, for example, after a final
tripping or other events which block the
auto reclose function after it has been started. Restarting is locked out for this time.
When this time expires, the automatic reclosure function returns to its quiescent state
and is ready for a new fault in the network.
If the circuit breaker is closed manually (by the control discrepancy switch connected
to a binary input, the local control functions or via one of the serial interfaces), the au-
tomatic reclosure is blocked for a manual-close-blocking time T-BLOCK MC, address
3404. If a trip command occurs during this time, it can be assumed that a metallic
short-circuit is present (e.g. closed earth switch). Every trip command within this time
is therefore final. With the user definable logic functions (CFC) further control functions
can be processed in the same way as a manual–close command.
Interrogation of the
Circuit Breaker
Ready State
A precondition for automatic reclosure following clearance of a short-circuit is that the
circuit breaker is ready for at least one OPEN-CLOSE-OPEN-cycle when the automat-
ic 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, the circuit-breaker interrogation can be sup-
pressed (presetting of address 3402) as automatic reclosure would otherwise not be
possible at all.
In the event of a single cycle reclosure this interrogation is usually sufficient. Since, for
example, the air pressure or the spring tension for the circuit breaker mechanism
drops after the trip, no further interrogation should take place.
Especially when multiple reclosing attempts are programmed, it is recommended to
monitor the circuit breaker condition not only prior to the first, but also before each fol-
lowing reclosing attempt. Reclosure will be blocked until the binary input indicates that
the circuit breaker is ready to complete another CLOSE-TRIP cycle.
The time needed by the circuit breaker to regain the ready state can be monitored by
the 7SD610. This monitoring time CB TIME OUT (address 3409) starts as soon as
the CB indicates the not ready state. The dead time may be extended if the ready state
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