CRG
t
200 ms
1
tSecurity
t
150 ms
>1
CR
CRL
LCG
AND
OR
t
AND
en05000746.vsd
IEC05000746 V1 EN-US
Figure 221: Guard signal logic with unblocking scheme and with setting
Unblock = Restart
OR
t
1
CR
CRG
CRL
tSecurity
IEC11000253-1-en.vsd
IEC11000253 V1 EN-US
Figure 222: Guard signal logic with unblocking scheme and with setting
Unblock = NoRestart
The unblocking function can be set in three operation modes (setting Unblock):
Off
The unblocking function is out of operation
No restart
Communication failure shorter than
tSecurity
will be ignored
If CRG 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
tSecurity
will be ignored
It sends a defined (150 ms) CRL after the disappearance of the CRG 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
12.1.6.6 Intertrip scheme
M13893-36 v5
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.
1MRK 506 382-UEN A Section 12
Scheme communication
Line distance protection REL650 2.2 IEC 439
Technical manual
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