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
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