Functions
2.7 Teleprotection for Distance Protection (optional)
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
195
Figure 2-88
Operation scheme of the permissive overreach transfer trip method
Sequence
The permissive overreach transfer trip only functions for faults in the „Forward“ direction. Accordingly, the first
overreach zone ZB1of the distance protection must definitely be set to
Forward
in addresses
1651
Op. mode
Z1B
, refer also to Section 2.5.2 under the margin heading „Controlled Zone ZB1“.
On two-terminal lines, the signal transmission can be phase selective. In this case, send and receive circuits
operate seperately for each phase. On three-terminal lines, the transmit signal is sent to both opposite line
ends. The receive signals are then combined with a logical AND gate, as all three line ends must transmit a
send signal during an internal fault.
With the parameter
Type of Line
(address
2102
) the device is informed as to whether it has one or two
opposite line ends (Figure 2-89).
During disturbance of the signal transmission path, the overreaching zone Z1B may be activated by an auto-
matic reclosure by setting parameter
1st AR -> Z1B
, and by an external recloser device via the binary input
„>Enable ARzones“
.
The occurrence of erroneous signals resulting from transients during clearance of external faults or from direc-
tion reversal resulting during the clearance of faults on parallel lines, is neutralized by the „Transient Blocking“.
On feeders with single-end infeed, the line end with no infeed cannot generate a release signal as no fault de-
tection occurs there. To achieve tripping by the permissive overreach transfer scheme also in this case, the
device features a special function. This „Weak Infeed Function“ (echo function) is described in Section „Mea-
sures for Weak and Zero Infeed“. It is activated when a signal is received from the opposite line end — in the
case of three terminal lines from at least one of the opposite line ends — without the device having detected a
fault.
The circuit breaker can also be tripped at the line end with no or only weak infeed. This „weak-infeed tripping“
is described in Section 2.11.2.
If the parameter
Mem.rec.sig.
(address
2113
) is set to
YES
and an own distance protection pickup is avail-
able in Z1B, the phase-selective release effected via the signal extension is stored. If the own distance protec-
tion pickup in Z1B drops out, it will be deleted.
