Siemens siprotec 7SA522 User Manual page 227

Sequence
7SA522 Manual
C53000-G1176-C119-2
A
Z1B(B)
Z1
(A)
T1
T1B
Z1B
&
(A)
further
zones
Figure 6-44 Operation scheme of the permissive underreach transfer trip method via Z1B
Figure 6-45 shows the logic diagram of the permissive underreach transfer trip
scheme for one line end.
The permissive transfer trip only functions for faults in the forward direction. Accord-
ingly, the first zone Z1 and the overreaching zone Z1B of the distance protection must
definitely be set to )RUZDUG: For distance protection with polygonal tripping charac-
teristic in address  2S PRGH = and  2S PRGH =%, refer also to Sub-
section 6.2.3.2 under the margin heading "Independent Zones Z1 up to Z5" and "Con-
trolled Zone Z1B"; for distance protection with MHO circles under address  2S
PRGH = and  2S PRGH =%, refer also to section 6.2.4.2 under margin head-
ing "Independent Zones Z1 up to Z5" and "Controlled Zone Z1B".
On two terminal lines, the signal transmission may be done phase segregated. On
three terminal lines, the transmit signal is sent to both opposite line ends. The receive
signals are then combined with an OR logic function. By means of the parameter /LQH
&RQILJ (address ) the device is informed whether it has one or two opposite
ends.
During disturbance of the signal transmission path, the overreaching zone Z1B may
be activated by an automatic reclosure via the binary input "!(QDEOH $5]RQHV" and
setting 1357 "1st AR -> Z1B" set to "Yes" (refer also to Figure 6-39 bottom).
If at one line end there is weak or zero infeed, so that the distance protection does not
pick up, the circuit breaker can still be tripped. This "weak-infeed tripping" is referred
to in Section 6.7.
Z1(B)
T
S
transm.
≥1
trip
rec..
Z1(A)
B
T
S
transm.
T1
T1B
≥1
&
trip
rec..
Functions
Z1B(A)
Z1
(B)
Z1B
(B)
further
zones
6-79