Siemens siprotec 7SA6, Manual

Page: 253 / 876

Functions
6-63
7SA6 Manual
C53000-G1176-C156-2
For the first zone, Z1, an additional tilt
α
(Figure 6-29) can be set by means of the pa-
rameter in address
1307 Zone Reduction
. This setting is required if short circuits
with a large fault resistance (e.g. overhead lines without earth/shield wire) are expect-
ed on lines with an infeed at both ends and load transfer in the direction of the line (ex-
port).
Different delay times can be set for single- and multiple-phase faults in the first zone:
T1-1phase
(address
1305
) and
T1-multi-phase
(address
1306
). The first zone
is typically set to operate without additional time delay.
The corresponding parameters for the higher zones are:
R(Z2)
(address
1312
),
X(Z2)
(address
1313
),
RE(Z2)
(address
1314
);
R(Z3)
(address
1322
),
X(Z3)
(address
1323
),
RE(Z3)
(address
1324
);
R(Z4)
(address
1332
),
X(Z4)
(address
1333
),
RE(Z4)
(address
1334
);
R(Z5)
(address
1342
),
X(Z5)+
(address
1343
) for forward direction, X
(Z5)-
(address
1346
) for reverse direction,
RE(Z5)
(address
1344
);
For the second zone it is also possible to set separate delay times for single- and multi-
phase faults. In general the delay times are set the same. If stability problems are ex-
pected during multiple-phase faults, a shorter time delay
T2-multi-phase
(address
1316
) may be considered under the given circumstances while a higher setting for
T2-1phase
(address
1315
) for single-phase faults may be tolerated.
The zone timers for the remaining zones are set with the parameters
T3 DELAY
(ad-
dress
1325
),
T4 DELAY
(address
1335
) and
T5 DELAY
(address
1345
).
If the device is provided with the capability to trip single-pole, single-pole tripping is
then possible in the zones Z1 and Z2. While single-pole tripping then usually applies
to single-phase faults in Z1(if the other conditions for single-pole tripping are satisfied),
this may also be selected for the second zone with address
1317A Trip 1pole Z2
.
Single pole tripping in zone 2 is only possible if this address is set to
YES.
The pre-
setting is
NO
.
Controlled Zone
Z1B The overreaching zone Z1B is a controlled zone. The normal zones Z1 to Z5 are not
influenced by Z1B. There is therefore no zone switching, but rather the overreaching
zone is activated or deactivated by the corresponding criteria. Z1B can also be select-
ed in address
1351
to be
Op. mode Z1B
=
Forward
,
Reverse
or
Non-Direc-
tional
. If this stage is not required, it is set to
Inactive
in address
1351
. The set-
ting options are similar to those of zone Z1: address
1352 R(Z1B) Ø-Ø
, address
1353 X(Z1B)
, address
1354 RE(Z1B) Ø-E
. The delay times for single-phase and
multiple-phase faults can again be set separately:
T1B-1phase
(address
1355
) and
T1B-multi-phase
(address
1356
).
Note:
For fast tripping (undelayed) in the forward direction the first zone Z1 should always
be used, as only the Z1 and Z1B are guaranteed to trip with the shortest operating
time of the device. The further zones should be used sequentially for grading in the
forward direction.
If fast tripping (undelayed) is required in the reverse direction, the zone Z3 should be
used for this purpose, as only this zone is guaranteed to trip with the shortest device
operating time for faults in the reverse direction. Zone Z3 is also recommended as re-
verse looking zone in teleprotection Blocking schemes.