Siemens siprotec 7SA6 User Manual page 244

Functions
Controlled Zone
Z1B
6-62
For the first zone, Z1, an additional tilt α (Figure 6-29) can be set by means of the
parameter in address  =RQH 5HGXFWLRQ. This setting is required if short circuits
with a large fault resistance (e.g. overhead lines without earth/shield wire) are
expected on lines with an infeed at both ends and load transfer in the direction of the
line (export).
Different delay times can be set for single- and multiple-phase faults in the first zone:
7SKDVH (address ) and 7PXOWLSKDVH (address ). The first zone
is typically set to operate without additional time delay.
The corresponding parameters for the higher zones are:
5 = (address ), ; = (address ), 5( = (address );
5 = (address ), ; = (address ), 5( = (address );
5 = (address ), ; = (address ), 5( = (address );
5 = (address ), ; =  (address ) for forward direction, X = 
(address ) for reverse direction, 5( = (address );
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
expected during multiple-phase faults, a shorter time delay 7PXOWLSKDVH
(address ) may be considered under the given circumstances while a higher
setting for 7SKDVH (address ) for single-phase faults may be tolerated.
The zone timers for the remaining zones are set with the parameters 7 '(/$<
(address ), 7 '(/$< (address ) and 7 '(/$< (address ).
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  7ULS SROH =.
Single pole tripping in zone 2 is only possible if this address is set to <(6 The
presetting is 12.
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.
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
selected in address  to be 2S PRGH =% = )RUZDUG, 5HYHUVH or 1RQ
'LUHFWLRQDO. If this stage is not required, it is set to ,QDFWLYH in address .
The setting options are similar to those of zone Z1: address  5 =% ‘‘,
address  ; =% , address  5( =% ‘(. The delay times for single-
phase and multiple-phase faults can again be set separately: 7%SKDVH (address
) and 7%PXOWLSKDVH (address ).
7SA6 Manual
C53000-G1176-C133-1