Siemens SIPROTEC 7SD80 Manual page 144

Functions
2.11 Automatic Reclosure Function 79 (Optional)
Processing the Auxiliary Contacts of the Circuit Breaker
If the circuit-breaker auxiliary contacts are connected to the device, the reaction of the circuit breaker is also
checked for plausibility.
If the series connections of the normally open and normally closed contacts of the poles are connected, the
circuit breaker is assumed to have all three poles open when the series connection of the normally closed con-
tacts is closed (binary input „>52b Bkr1 3p Op", no.411). All three poles are assumed closed when the
series connection of the normally open contacts is closed (binary input „>52a Bkr1 3p Cl", no. 410).
The device continuously checks the switching state of the circuit breaker: As long as the auxiliary contacts in-
dicate that the CB is not closed in all 3 poles, the automatic reclosure function cannot be started. A close
command is only issued if the circuit breaker tripped previously (from of the closed state).
The valid dead time begins if no trip command applies, or if the auxiliary contacts additionally indicate that the
circuit breaker has opened.
Sequence of a 3-Pole Automatic Reclose Cycle
If the automatic reclosure function is ready, the fault protection trips for all faults inside the element selected for
reclosure. The automatic reclosure function is started. When the trip command resets or the circuit breaker
opens (auxiliary contact criterion) a configurable dead time is started. At the end of this dead time, the circuit
breaker receives a close command. At the same time, the configurable blocking time is started. If, when con-
figuring the protective functions, at address 134 AR control mode = with Pickup was set, different dead
times can be parameterized depending on the type of fault recognized by the protection.
If the fault is cleared (successful reclosure), the restraint time expires and all functions return to their quiescent
state. The fault is terminated.
If the fault has not been eliminated (unsuccessful reclosure), the short-circuit protection initiates a final trip fol-
lowing a protection stage active without reclosure. Any fault during the restraint time leads to a final trip.
After unsuccessful reclosure (final tripping) the automatic reclosure is blocked dynamically (see also margin
heading „Reclose Block, above").
The sequence above applies for single reclosure cycles. 7SD80 allow 2 reclosing cycles.
Multiple Automatic Reclosing Attempts
If a short circuit still exists after a reclosing attempt, one more reclosing attempt can be made.
The two reclosing cycles are independent of each other. Each has separate action and dead times and can be
blocked separately via binary inputs.
The sequence is basically the same as described above. However, if the first reclosure attempt was unsuc-
cessful, the reclosure function is not blocked, but instead the second reclose cycle is started. The appropriate
dead time starts with the reset of the trip command or opening of the circuit breaker (pole) (auxiliary contact
criterion). The circuit breaker receives a new close command after expiry of the dead time. At the same time
the restraint time is started.
The restraint time is reset with each new trip command after reclosure and is started again with the next close
command until the set maximum number of permissible automatic reclosing cycles has been reached.
If one of the two reclosing attempts is successful, i.e. the fault disappeared after reclosing, the blocking time
expires and the automatic reclosing system is reset. The fault is terminated.
If no cycle is successful, the short-circuit protection initiates a final trip after the last permissible reclosing, fol-
lowing the grading time valid without reclosing. The automatic reclosing function is blocked dynamically (see
also above under margin heading „Blocking the Reclosing Function").
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SIPROTEC, 7SD80, Manual
E50417-G1140-C474-A1, Release date 09.2011