ABB REL670 2.2 IEC Applications Manual page 824

Section 21
Station communication
818
local
IED
MU
IEC13000298 V2 EN-US
Figure 409: Normal operation
Case 2:
Failure of the MU (sample lost) blocks the sending of binary signals through
LDCM. The received binary signals are not blocked and processd normally.
→DTT from the remote end is still processed.
local
IED
MU
IEC13000299 V2 EN-US
Figure 410: MU failed, mixed system
Case 3:
Failure of one MU (sample lost) blocks the sending and receiving of binary signals
through LDCM.
→DTT from the remote end is not working.
Direct transfer trip (DTT)
OK
OK
IEC13000298-2-en.vsd
Direct transfer trip (DTT)
Not OK
OK
IEC13000299-2-en.vsd
1MRK 506 369-UEN B
remote
IED
remote
IED
Line distance protection REL670 2.2 IEC
Application manual