Siemens Siprotec 7VK61 Manual page 48

Functions
2.2 Automatic reclosure function (optional)
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 reclaim 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. In 7VK61 multiple reclosure (up to 8 shots) is also
possible (see below).
Sequence of a single-pole reclose cycle
Single-pole reclose cycles are only possible if the external protection device and the Breaker Management
Device 7VK61 relay are suitable for single-pole tripping and if single-pole tripping was enabled during configu-
ration of the protection functions (address 110 Trip mode = 1-/3pole, see also Section 2.1.1.2). Of course,
the circuit-breaker must also be suitable for single-pole tripping.
If the automatic reclosure function is ready, the short-circuit protection trips single pole for all single-phase faults
inside the stage selected for reclosure. Single-pole tripping is of course only possible by fault protection func-
tions which can determine the faulted phase.
If only single-pole reclosure is selected then the fault protection issues a final three pole trip with the stage that
is valid/selected without reclosure. Any three-pole trip is final. The automatic reclose function is blocked dy-
namically (see also above at margin heading "Blocking of Auto-reclosure").
The automatic reclosure is started in the case of single-pole tripping. The (adjustable) dead time for the single-
pole reclose cycle starts with reset of the trip command or opening of the circuit breaker pole (auxiliary contact
criterion). After expiry of the dead time, the circuit breaker receives a close command. At the same time, the
(adjustable) blocking time is started. If the reclosure is blocked during the dead time following a single-pole trip,
immediate three-pole tripping can take place as an option (forced three-pole trip).
If the fault is cleared (successful reclosure), the reclaim time expires and all functions return to their quiescent
state. The fault is cleared.
If the fault has not been eliminated (unsuccessful reclosure), the short-circuit protection initiates a final three-
pole trip following the protection stage valid without reclosure. Any fault during the blocking time leads to a final
three-pole 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. In 7VK61 multiple reclosure (up to 8 shots) is also
possible (see below).
Sequence of a single- and three-pole reclose cycle
This operating mode is only possible if the responsible protection device and the Breaker Management
Device7VK61 are suitable for single-pole tripping and if single-pole tripping was enabled during configuration
(address 110, see also section 2.1.1.2). Of course, the circuit-breaker must also be suitable for single-pole trip-
ping.
If the automatic reclosure function is ready, the fault protection trips single-pole for single-phase faults and
three-pole for multi-phase faults. Single-pole tripping is of course only possible with fault protection functions
that can determine the faulted phase. The valid protective element selected for reclosure ready state applies
for all fault types.
The automatic reclosure is started at the moment of tripping. Depending on the type of fault, the (adjustable)
dead time for the single-pole reclose cycle or the (separately adjustable) dead time for the three-pole reclose
cycle starts following the reset of the trip command or opening of the circuit breaker (pole) (auxiliary contact
criterion). After expiry of the dead time, the circuit breaker receives a close command. At the same time, the
(adjustable) blocking time is started. If the reclosure is blocked during the dead time following a single-pole trip,
immediate three-pole tripping can take place as an option (forced three-pole trip).
48
SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009