Siemens SIPROTEC 7SJ62 Manual page 254

Functions
2.14 Automatic Reclosing System 79
With the final reclosing attempt, i.e. when no automatic reclosing is expected, protection is to trip with delay
according to the grading coordination chart of the system, since selectivity has priority.For details see also in-
formation at margin heading "Interaction with the Automatic Reclosing Function" which can be found with the
setting notes of the overcurrent protection functions and the functional description of the intermittent ground
fault protection.
Single-shot Reclosing
When a trip signal is programmed to initiate the auto-reclosure, the appropriate automatic reclosing program
will be executed. Once the circuit breaker has opened, a dead time interval in accordance with the type of fault
is started (see also margin heading "Reclosing Programs"). Once the dead time interval has elapsed, a closing
signal is issued to reclose the circuit breaker. A blocking time interval TIME RESTRAINT is started at the same
time. Within this restraint time it is checked whether the automatic reclosure was performed successfully. If a
new fault occurs before the restraint time elapses, the automatic reclosing system is dynamically blocked
causing the final tripping of the circuit breaker. The dead time can be set individually for each of the two reclos-
ing programs.
Criteria for opening the circuit breaker may either be the auxiliary contacts of the circuit breaker or the dropout
of the general device pickup if auxiliary contacts are not configured.
If the fault is cleared (successful reclosing attempt), the blocking time expires and automatic reclosing is reset
in anticipation of a future fault. The fault is terminated.
If the fault has not been cleared (unsuccessful reclosing attempt), then a final trip signal is initiated by one or
more protective elements.
Multi-shot Reclosing
7SJ62/64 permits up to 9 reclosings. The number can be set differently for the phase fault reclosing program
and the ground fault reclosing program.
The first reclose cycle is, in principle, the same as the single-shot auto-reclosing. If the first reclosing attempt
is unsuccessful, this does not result in a final trip, but in a reset of the restraint time interval and start of the next
reclose cycle with the next dead time. This can be repeated until the set number of reclosing attempts for the
corresponding reclose program has been reached.
The dead time intervals preceding the first four reclosing attempts can be set differently for each of the two re-
closing programs. The dead time intervals preceding the fifth reclosing attempts will be equal to the dead time
interval that precedes the fourth reclosing attempt.
If one of the reclosing attempts is successful, i.e. the fault disappeared after reclosure, the restraint time expires
and the automatic reclosing system is reset. The fault is cleared.
If none of the reclosing attempts is successful, then a final circuit breaker trip (according to the grading coordi-
nation chart) will take place after the last allowable reclosing attempt has been performed by the protection
function. All reclosing attempts were unsuccessful.
After the final circuit breaker tripping, the automatic reclosing system is dynamically blocked (see below).
Blocking Time
The function of the blocking time has already been described under section "Single-/Multi-Shot Reclosing". The
blocking time can be prolonged if the following conditions have been fulfilled.
The time 211 TMax CLOSE CMD defines the maximum time during which a close command can apply. If a new
trip command occurs before this time has run out, the close command will be aborted. If the time TMax CLOSE
CMD is set longer than the restraint time TIME RESTRAINT, the restraint time will be extended to the remaining
close command duration after expiry!
A pickup from a protection function that is set to initiate the automatic reclosing system will also lead to an ex-
tension of the blocking time should it occur during this time!
254
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008