Siemens SIPROTEC 7SA522 Manual page 100

2 Functions
Controlled zone
Z1B
Polarization
100
Note
For instantaneous 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 instantaneous tripping (undelayed) is required in the reverse direction, the zone Z3
should be used for this purpose, as only this zone is ensures instantaneous pickup
with the shortest device operating time for faults in the reverse direction. This setting
is also recommended in teleprotection %/2&.,1* schemes.
With binary input indications 3619 ´!%/2&. = 3K(µ and 3620 ´!%/2&. = 3K
(µ zones Z4 and Z5 for phase-earth loops may be blocked. To block these zones per-
manently for phase-earth loops, said binary inputs must be set to the logic value of 1
via CFC.
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. It can also be set 
= 2S PRGH =% at address )RUZDUG or 5HYHUVH. 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 =% . The delay times for single-phase and multiple-phase faults
can again be set separately: 7%SKDVH (address ) and 7%PXOWLSKDVH
(address ).
Zone Z1B is usually used in combination with automatic reclosure and/or teleprotec-
tion schemes. It can be activated internally by the teleprotection functions (see also
Section 2.6) or the integrated automatic reclosure (if available, see also Section 2.13)
or externally by a binary input. It is generally set to at least 120 % of the line length.
On three-terminal line applications ("teed feeders"), it must be set to securely reach
beyond the longest line section, even when there is additional infeed via the tee-off
point. The delay times are set in accordance with the type of application, usually to
zero or a very small delay. When used in conjunction with teleprotection comparison
schemes, the dependence on the fault detection must be considered (refer to margin
heading "Distance Protection Prerequisites" in Subsection 2.6.10.
If the distance protection is used in conjunction with an automatic recloser, it may be
determined in address  VW $5 ! =% which distance zones are released prior
to a rapid automatic reclosure. Usually the overreaching zone Z1B is used for the first
cycle VW $5 ! =% = <(6). This may be suppressed by changing the setting of
VW $5 ! =% to 12. Then the overreaching zone Z1B with the automatic reclosure
function ready is is not released. Zone Z1 is always released. The setting only has an
effect when the service condition of the automatic reclose function is input to the
device via binary input ´!(QDEOH $5]RQHVµ (FNo. 383).
For Ph-E loops the degree of the polarization with a fault-accurate memory voltage
can be set in address  0HP3RODUL]3K( and in address 
0HP3RODUL]33 for Ph-Ph loops. With an unfaulted valid voltage (cross-polariza-
tion) the evaluation factor can be set separately for Ph-E and Ph-Ph in address 
&URVV3RODUL]3K( and  &URVV3RODUL]33. This setting can only be
®
changed via DIGSI at Additional Settings.
These parameters have an impact on the expansion of the circles depending on the
source impedance. If the parameter is set to zero, you get the basic circle without ex-
pansion.
7SA522 Manual
C53000-G1176-C155-3