ABB RELION REX640, Technical Manual, Page: 1242 / 1960

response times in transmitting the
CS_BLOCKING
signal to the other
feeder end. The
Coordination Time setting must not be zero.
Activating the
BLOCK
input totally blocks the directional comparison blocking
scheme. The
CS_PRM
and
OPERATE
outputs can be blocked by the
BLK_CS_OPR
input.
In
Figure 707
, in case of internal faults, the
CS_BLOCKING
signal is not sent because
the fault is not sent as it is not seen by the reverse-looking zones (Z3).
~
~
Z1
Z2
Z1
Z2
Z3
Z3
Z2_START
TRIP_CB_A
TRIP_CB_B
Z2_START
Bus A Bus B
3
3
Figure 707: Simplified functional diagram of the blocking scheme, internal fault
In Figure 708 , in case of external faults, the protection relay at bus B sees the fault
in the reverse direction and sends a blocking signal
CS_BLOCKING
to the protection
relay at bus A. There is no CB operation at either end.
Protection related functions 1MRS759142 F
1242 REX640
Technical Manual