ABB RELION REX640 Technical Manual page 1256

Protection related functions
settable
terminal. To prevent a false trip in case of external faults, the CR_BLOCKING signal
must be received before the
the overreaching residual overcurrent function DEFLPDEF is connected to the CACC
input.
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.
Figure 714
In
fault is not seen by the reverse-looking overreaching function.
Bus A
~
DEFL_START
(Forward)
Figure 714: Simplified functional diagram of the blocking scheme, internal fault
Figure 715
In
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.
1256
Coordination time , and if no block signal is received from the remote
The Coordination time setting in the blocking scheme depends, for
example, on the communication system delay and on the terminal's
response times in transmitting a CS_BLOCKING signal to the other feeder
Coordination time setting must not be zero.
end. The
, in case of internal faults, the CS_BLOCKING signal is not sent as the
3
TRIP_CB_A
, in case of external faults, the protection relay at bus B sees the fault
Coordination time has elapsed. The start signal from
DEFL_START
(Forward)
1MRS759142 F
Bus B
~
3
TRIP_CB_B
REX640
Technical Manual