Siemens Siprotec 7VK61 Manual page 46

Functions
2.2 Automatic reclosure function (optional)
reclosure operating mode selected when determining the function scope and the resulting signals of the starting
protective functions.
In control mode TRIP... (With TRIP command ...) single-pole or single-/three-pole reclose cycles are possible
if the device and the circuit breaker are suitable. In this case, different dead times (for every AR cycle) are pos-
sible after single-pole tripping and after three-pole tripping. The protective function that issues the trip command
determines the type of trip: Single-pole or three-pole. The dead time is controlled dependent on this.
In control mode PICKUP ... (With PICKUP...) different dead times can be set for every reclose cycle after
single-, two- and three-phase faults. Here the decisive factor is the pickup diagram of the protective functions
at the instant the trip command disappears. This mode enables to make the dead times dependent on the type
of fault in the case of three-pole reclose cycles.
Blocking reclosure
Different conditions lead to blocking of the automatic reclosure. No reclosure is possible, 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 concerned is declared as
invalid and will be skipped in the sequence of permissible cycles. If blocking takes place while the cycle con-
cerned 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 reclosure 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 suc-
cessful, 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 qui-
escent 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 automatic 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 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, the circuit-breaker interrogation can be suppressed (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 pres-
sure or the spring tension for the circuit breaker mechanism drops after the trip, no further interrogation should
take place.
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SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009