Siemens siprotec 7SA6 User Manual page 603

Reverse
Interlocking
Permissive
Overreach
Transfer,
Unblocking
7SA6 Manual
C53000-G1176-C133-1
'LV must be set to (QDEOHG in Address . The protection relays at both line
ends must be operating. First the quiescent current loop of the pilot wire comparison
is not supplied with auxiliary voltage.
A fault is simulated outside of zone Z1, but within zone Z1B. Since stage Z1B is
blocked, the Distance Protection is only tripped in a higher-leveled zone (usually with
T2). This check must be carried out at both line ends.
The direct voltage for the quiescent current loop of the pilot wire comparison is
switched to the line. The loop is then fed with quiescent current.
At one line end a fault is simulated outside of the first zone, but within the overreach
zone Z1B. The command is tripped to T1B. This check must be carried out at both line
ends.
Since the quiescent current loop is part of the nature of the pilot wire comparison,
these tests also check if the transmission process is performed correctly. All further
tests described in Subsubsection 8.3.12.1 can be passed over. However, please refer
to the last margin heading "Important for All Schemes"!
The checking of the reverse interlocking is described below. If a different transmission
scheme is applied, this part can be skipped.
For more detailed information about the reverse interlocking see Subsubsection
6.4.1.9.
For 7HOHSURWHFWLRQ IRU 'LVWDQFH SURW 7HOHSURW 'LVW set
5HYHUVH ,QWHUORFNLQJ in Address  (Subsection 5.1). Furthermore the )&7
7HOHS () must be set to HQDEOHG in Address . The Distance Protection of
the infeed and switchgears of all outgoing feeders must operate. At the beginning no
auxiliary voltage is fed to the line for the reverse interlocking.
The following paragraphs describe the testing in a blocked state, i.e. the pick-up
signals of the outgoing devices are connected in parallel and block the tested device
of the infeed. In case of release (the NC contacts of the outgoing devices are
connected in series) the tests have to be reinterpreted respectively.
A fault is simulated within zone Z1 and overreaching zone Z1B. As a result of the
missing blocking signal, the distance protection trips after time delay T1B (slightly
delayed).
Now, the direct voltage for the reverse interlocking is switched in. The test is repeated
as described above and ends up with the same result.
At each of the protection devices of the outgoing circuits, a pick-up is simulated.
Meanwhile, another short-circuit is simulated as described before for the distance
protection of the infeed. Now, the distance protection trips after time T1, which has a
longer setting.
These tests also check the proper functioning of the transmission path. All other tests
which are described in this Subsection 8.3.12.1 are no more necessary. However,
please refer to the last margin heading "Important for All Schemes"!
Prerequisite: 7HOHSURWHFWLRQ IRU 'LVWDQFH SURW 7HOHSURW 'LVW is
set in address  (Section 5.1) to one of the permissive overreach schemes with a
release signal, 3HUPLVVLYH 2YHUUHDFK or 'LUHFWLRQDO &RPSDULVRQ 3LFNXS
or 81%/2&.,1*; furthermore, the parameter in address  must be set to )&7
7HOHS () 21. Naturally, the corresponding send and receive signals must also be
assigned to the corresponding binary output and input. For the echo function, the echo
signal must be assigned separately to the transmit output!
Installation and Commissioning
8-59