ABB RELION REX640 Technical Manual page 1151

1MRS759142 C
REX640
Technical Manual
In Figure 620, 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).
Z3
Bus A
~
3
Z2_START
GUID-41FB8590-EDBD-4EBB-A99C-0E0CBFB7E9C0 V1 EN
Figure 620: Simplified functional diagram of the blocking scheme, internal fault
In Figure 621, 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.
Z3
Bus A
~
3
Z2_START
GUID-D6308D07-F72A-4B2A-9E04-2B25050647DA V1 EN
Figure 621: Simplified functional diagram of the blocking scheme, external fault
Protection related functions
Z2
Z1
Z1
Z2
TRIP_CB_A
Z2_START
Z2
Z1
Z1
Z2
Z3_START
Section 5
Bus B
~
3
Z3
TRIP_CB_B
Bus B
~
3
Z3
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