Siemens siprotec 7SA522, User Manual

Page: 230 / 628

Functions
6-82
7SA522 Manual
C53000-G1176-C119-2
The transmit signal can be prolonged by T
S
(settable under address
6HQG3UR
ORQJ
). This extension of the transmit signal is only active when the protection has
already issued a trip command. This ensures the release of the opposite line end,
even when the short-circuit has been locally cleared very fast by the independent zone
Z1.
For all zones, except for Z1B, the tripping takes place without a release signal from
the opposite line end. This allows the protection to operate with the normal grading
characteristic independent of the signal transmission.
Figure 6-47 Operation scheme of the permissive overreach transfer trip method
Sequence Figure 6-48 shows the logic diagram of the signal comparison scheme for one line
end.
The permissive overreach transfer trip only functions for faults in the forward direction.
Accordingly, the overreaching zone Z1B of the distance protection must definitely be
set to
)RUZDUG
: In the case of distance protection with polygonal characteristic, in ad-
dress
2SPRGH=
, refer also to Sub-section 6.2.3.2 under margin heading
“Controlled Zone Z1B”; In the case of distance protection with MHO characteristic, in
address
2SPRGH=%
, refer also to Sub-section 6.2.4.2 under margin head-
ing “Controlled Zone Z1B”.
On two terminal lines, the signal transmission may be phase segregated. Send and
receive circuits in this case are built up for each phase. On three terminal lines the
send signal is transmitted to both opposite ends. The receive signals are then com-
bined with the logical
AND function, as all three line ends must transmit during an in-
ternal fault. Via the setting
/LQH&RQILJ
(address ) the device is informed as
to whether it has one or two opposite line ends.
In the case of faults in the transmission path, the overreaching zone Z1B can be acti-
vated by an automatic reclose device, via the binary input “
!(QDEOH$5]RQHV
” and
setting 1357 “1st AR -> Z1B” set to “Yes” (refer to Figure 6-39 bottom).
The occurrence of erroneous signals resulting from transients during clearance of ex-
ternal faults or from direction reversal resulting during the clearance of faults on par-
allel lines, is neutralized by the “Transient Blocking” (refer to Sub-section 6.4.1.6).
On feeders with single-sided infeed, the line end with no infeed cannot generate a re-
lease signal, as no fault detection occurs there. To achieve tripping by the permissive
overreach transfer scheme even in this case, the device contains a special function.
T1B
Z1B
receive.
transmit
A B
Z1(A)
Z1(B)
Z1B(A)
Z1B(B)
T
S
&
≥
1
trip
receive.
further
zones
&
Z1 or
≥
1
T
S
&
trip
transmit
further
zones
&
Z1 or
≥
1
(A)
T1B
Z1B
(B)
≥
1