2.6 Teleprotection for distance protection
133
7SA522 Manual
C53000-G1176-C155-3
In protective relays equipped with a protection data interface, address
7HOHSURW'LVW allows to set 6,*1$/Y3URW,QW. At address )&7
7HOHS'LV 3277 can be set.
Figure 2-51 Function diagram of the permissive overreach transfer trip method
Sequence The permissive overreach transfer trip only functions for faults in the “forward” direc-
tion. Accordingly, the first overreach zone ZB1 of the distance protection must definite-
ly be set to )RUZDUG in addresses 2SPRGH=%, refer also to Subsection
2.2.2 under the margin heading “Controlled Zone ZB1”.
On two terminal lines, the signal transmission may be phase segregated. Send and
receive circuits in this case are built up for each phase. On three terminal lines, the
transmit signal is sent to both opposite line ends. The receive signals are then com-
bined with a logical AND gate, as all three line ends must transmit a send signal during
an internal fault. If parameter 7HOHSURW'LVW (address ) is set to
6,*1$/Y3URW,QW and parameter 180%(52)5(/$< (address ) to UHOD\V,
the device is informed about two remote ends. The default setting is UHOD\V, which
corresponds to one remote end. In protective relays equipped with one protection data
interface, signal transmission is always phase segregated (Figure 2-53 and 2-54).
If conventional transmission is used, parameter 7\SHRI/LQH (address )
informs the device whether it has one or two opposite line ends (Figure 2-52).
During disturbance of the signal transmission path, the overreaching zone Z1B may
be activated by an automatic reclosure (internal or external) via the binary input
´!(QDEOH$5]RQHVµ.
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”.
On feeders with single-sided infeed, the line end with no infeed cannot generate a
release signal, as no fault detection occurs there. To achieve tripping by the permis-
sive overreach transfer scheme even in this case, the device contains a special func-
tion. This “Weak Infeed Function” (echo function) is referred to in Subsection “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.
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