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Functions
2.7 Teleprotection for Distance Protection (optional)
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
193
On two terminal lines, the signal transmission may be phase-selective. In this case, send and receive circuits
are built up for each phase. 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.
With the parameter Type of Line (address 2102 ) the device is informed as to whether it has one or two
opposite line ends.
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“ .
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.
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 described in Section 2.11.2.
2.7.5 Direct Underreach Transfer Trip
Principle
As is the case with PUTT (pickup) or PUTT with zone acceleration, a fault in the first zone Z1 is transmitted to
the opposite line end by means of a transfer trip signal. The signal received there causes a trip without further
queries after a short security margin Tv (settable in address
2202 Trip Time DELAY ) (Figure 2-87). The
transmit signal can be prolonged by T
S
(settable in address 2103 Send Prolong. ), to compensate for pos-
sible differences in the pickup time at the two line ends. The distance protection is set such that the first zone
reaches up to approximately 85% of the line length. On three terminal lines Z1 is also set to approximately 85 %
of the shorter line section, but at least beyond the tee-off point. Care must be taken to ensure that Z1 does not
reach beyond one of the two other line ends. The overreaching zone Z1B is not required here. It may, however,
be activated by internal automatic reclosure or external criteria via the binary input
„>Enable ARzones“ .
The advantage compared to the other permissive underreach transfer trip schemes lies in the fact that both line
ends are tripped without the necessity for any further measures, even if one line end has no infeed. There is
however no further supervision of the trip signal at the receiving end.
The direct underreach transfer trip application is not provided by its own selectable teleprotection scheme set-
ting, but implemented by setting the teleprotection supplement to operate in the permissive underreach transfer
trip scheme (address
121 Teleprot. Dist. = PUTT (Z1B) or PUTT (Pickup) ), and using the binary
inputs for direct external trip at the receiving end. Correspondingly, the transmit circuit in Section „The principle
of PUTT“ (Figure 2-84) applies. For the receive circuit the logic of the „external trip“ as described in Section
2.12 applies.
On two terminal lines, the signal transmission may be phase segregated. In this case, send and receive circuits
operate separately for each phase. On three terminal lines, the transmit signals are sent to both opposite line
ends. The receive signals are then combined with a logical OR function.