ABB Relion 670 Series Technical Reference Manual page 798

Section 13
Scheme communication
13.1.2.5
13.1.2.6
792
CR
NOT
CR_GUARD
200 ms
0
ANSI05000746 V1 EN
Figure 388: Guard signal logic with unblocking schemeGuard singal logic with
unblocking scheme and with setting Unblock = Restart
The unblocking function can be set in three operation modes (setting Unblock):
Disabled
The unblocking function is out of operation
No restart
Communication failure shorter than
If CR_GUARD disappears a CRL signal will be transferred to the trip logic
There will not be any information in case of communication failure (LCG)
Restart
Communication failure shorter than
It sends a defined (150 ms) CRL after the disappearance of the CR_GUARD signal
The function will activate LCG output in case of communication failure
If the communication failure comes and goes (<200 ms) there will not be recurrent
signalling
Intertrip scheme
In the direct intertrip scheme, the send signal CS is sent from an underreaching zone
that is tripping the line.
The received signal CR is directly transferred to a TRIP for tripping without local
criteria. The signal is further processed in the tripping logic.
In case of single-pole tripping in multi-phase systems, a phase selection is performed.
Simplified logic diagram
The simplified logic diagram for the complete logic is shown in figure 389.
0-tSecurity
0
150 ms
OR
AND
0
tSecurity will be ignored
tSecurity will be ignored
1MRK505222-UUS C
CRL
OR
AND
LCG
en05000746_ansi.vsd
Technical reference manual