Setting The Function Parameters - Siemens siprotec 7SA6 User Manual

Functions

6.12.2 Setting the function parameters

General
6-184
If no reclosure is required on the feeder to which the distance protection 7SA6 is
applied (e.g. for cables, transformers, motors or similar), the automatic reclosure
function must be removed during configuration of the device (see Section 5.1, address
). The automatic reclosure function is then completely disabled, i.e. the
automatic reclosure is not processed in the 7SA6. No signals regarding the reclosure
function are generated and the binary inputs for the automatic reclosure function are
ignored. All parameters for setting the automatic reclosure function are inaccessible
and of no significance. Tripping is always three-pole for all faults.
If, on the other hand, the internal automatic reclosure function is to be used, the type
of reclosure must be selected during the configuration of the functions (see Section
5.1) in address  $XWR 5HFORVH and the $5 FRQWURO PRGH in address .
Up to 8 reclosure attempts are allowed with the integrated automatic reclosure
function in the 7SA6. Whereas the settings in the addresses  to  are
common to all reclosure cycles, the individual settings of the cycles are made from
address  onwards. It is therefore possible to set different individual parameters
for the first four reclose cycles. The parameters of the fourth cycle also apply to the
fifth cycle and onwards.
Under address  $872 5(&/26( the automatic reclosure function can be
switched 2Q or 2II.
A prerequisite for automatic reclosure taking place after a trip due to a short-circuit is
that the circuit-breaker is ready for at least one TRIP–CLOSE–TRIP–cycle at the time
the automatic reclosure is started (i.e. at the time of the first trip command). The
readiness of the circuit-breaker is signalled to the device through the binary input
"!&% 5HDG\" (F.No ). If no such signal is available, leave the setting under
address  &%" 75,3 = 1R because no automatic reclosure would be possible
at all otherwise. If circuit-breaker readiness can be interrogated, the setting &%"
75,3 = <HV should be applied.
Furthermore the circuit-breaker ready state can also be interrogated prior to every
reclosure. This is set when setting the individual reclose cycles (see below).
To check if the circuit-breaker is ready again during the dead times, it is possible to set
a circuit-breaker–ready–monitor time under address  &% 7,0( 287. This time
is set slightly longer than the recovery time of the circuit-breaker after a TRIP–
CLOSE–TRIP–cycle. If the circuit-breaker is not ready again by the time this timer
expires, no reclosure takes place, the automatic reclosure function is blocked
dynamically.
Waiting for the circuit-breaker to be ready can lead to an increase of the dead times.
Interrogation of a synchro–check (if used) can also delay reclosure. To avoid
uncontrolled prolongation it is possible to set a maximum prolongation of the dead
time in this case under address $ 7'($' (;7. This prolongation is unlimited
if the setting ∞ is applied. This setting can only be changed with DIGSI
"Additional Settings". Remember that longer dead times are only permissible after
three-pole tripping when no stability problems arise or when a synchro–check takes
place before reclosure.
The reclaim time 75(&/$,0 (address ) is the time after which the system fault
is considered to be over after a successful reclosure. Re-tripping of a protection
function within this time initiates the next reclose cycle in the event of multiple
reclosure; if no further reclosure is permitted, the last reclosure is treated as
unsuccessful. The reclaim time must therefore be longer than the longest response
time of a protective function which can start the automatic reclosure function.
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7SA6 Manual
C53000-G1176-C133-1