Siemens siprotec 7SA6, Manual

Page: 297 / 876

Functions
6-107
7SA6 Manual
C53000-G1176-C156-2
Sequence Figure 6-63 shows the logic diagram of the blocking scheme for one line end.
The relevant distance zone for this scheme is the overreach zone Z1B. Its reach di-
rection must therefore be set to
Forward
: address
1351 Op. mode Z1B
, refer also
to Sub-section 6.2.4.2 under margin heading “Controlled Zone Z1B”.
On lines with two ends, 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 signal are then com-
bined with the logical OR function, as in the case of an internal fault, no blocking signal
must be received from any line end. Via the setting
Line Config.
(address
2102
)
the device is informed as to whether it has one or two opposite line ends.