Functions
2.11 Automatic Reclosure Function 79 (Optional)
SIPROTEC, 7SD80, Manual
E50417-G1140-C474-A1, Release date 09.2011
143
Blocking the Reclosing Function
Different conditions lead to blocking of the automatic reclosing function. No reclosing is possible, for example,
if it is blocked via a binary input. If the automatic reclosing function has not been started yet, it cannot be started
at all. If a reclosing cycle is already in progress, dynamic lockout 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 is skipped in the sequence of permissible cycles. If blocking takes place while the affected cycle is
already running, this causes the reclosing to be canceled, i.e. no reclosing takes place even if other valid cycles
have been parameterized.
Internal blocking states restricted to certain time periods are processed during the course of reclosing cycles:
The restraint time
T-RECLAIM
(address
3403
) is started with each automatic reclosing command. The only
exception is the ADT mode where the blocking time can be disabled by setting it to 0 s. If reclosing is success-
ful, all the functions of the automatic reclosing function return to the quiescent state at the end of the restraint
time; a fault after expiry of the blocking time is treated as a new fault in the system. If the restraint time is dis-
abled in ADT mode, each new trip after reclosing is considered as a new fault. If one of the protection functions
causes another trip during the restraint time, the next reclosing cycle will be started if multiple reclosing at-
tempts have been set. If no further reclosing attempts are permitted, the last reclosing attempt is regarded as
unsuccessful in case of another trip during the restraint time. The automatic reclosure is blocked dynamically.
The dynamic blocking locks the reclosure for the duration of the dynamic blocking time (0.5 s). This occurs, for
example, after a final trip or other events which block the auto reclose function after it has been started. Re-
starting is blocked during this time. When this time expires, the automatic reclosing 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 reclosing is blocked for a manual-close-
blocking time
BLOCK MC Dur.
, 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
a final trip. With the user-definable logic functions (CFC) further control functions can be processed in the same
way as a manual close command.
Scanning of the Readiness of the Circuit Breaker
A precondition for automatic reclosing following clearance of a short circuit is that the circuit breaker is ready
for at least one OPEN-CLOSE-OPEN-cycle when the automatic reclosing circuit is started (i.e. at the time of
the first trip command). The readiness of the circuit breaker is signaled to the device via the binary input
„>Bkr1 Ready“
(no. 371). If no such signal is available, the circuit-breaker interrogation can be suppressed
(presetting of address
3402
) as automatic reclosing 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.
Especially when multiple reclosing attempts are programmed, it is a good idea to monitor the circuit-breaker
condition not only prior to the first but also before the second 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 7SD80. This moni-
toring 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 is not indicated when it expires. However, if the circuit breaker does
not indicate its ready status for a longer period than the monitoring time, reclosure is dynamically blocked (see
also above under margin heading „Blocking the Reclosing Function“).
