Siemens siprotec 7SA522, User Manual

Page: 316 / 628

Functions
6-168
7SA522 Manual
C53000-G1176-C119-2
6.11.2 Setting the function parameters
General If no reclosure is required on the feeder to which the Distance Protection 7SA522 is
applied (e.g. for cables, transformers, motors or similar), the automatic reclosure func-
tion 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 function is not processed in the 7SA522. No signals regarding the
recloser function are generated and the binary inputs for the automatic reclosure func-
tion are ignored. All parameters for setting the automatic reclosure function are inac-
cessible 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
$XWR5HFORVH
and the
$5FRQWUROPRGH
in address .
Up to 8 reclosure attempts are allowed with the integrated automatic reclosure func-
tion in the 7SA522. 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
$8725(&/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 circuit 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 ad-
dress
&%"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 re-
closure. 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 regeneration time of the circuit-breaker after a TRIP–
CLOSE–TRIP–cycle. If the circuit-breaker is not ready again by the time this timer ex-
pires, no reclosure takes place, the automatic reclosure function is blocked dynami-
cally.
Waiting for the circuit-breaker to be ready can lead to an increase of the dead times.
Interrogation of a sync. 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'($'(;7
. This prolongation is unlimited if the setting
∞
is
applied. This setting can only be modified with DIGSI
®
4 under “Additional Settings”.
Remember that longer dead times are only permissible after three-pole tripping when
no stability problems arise or when a sync. check takes place before reclosure.
The reclaim time
75(&/$,0
(address ) is the time after which the system dis-
turbance is considered to be over after a successful reclosure. Re-tripping of a protec-
tion function within this time initiates the next reclose cycle in the event of multiple re-
closure; if no further reclosure is permitted, the last reclosure is treated as unsuccess-
ful. The reclaim time must therefore be longer than the longest response time of a pro-
tective function which can start the automatic reclosure circuit.