GE MiCOM P40 Agile Technical Manual page 257

P543i/P545i
DDB signal (Opto-input)
Input L3 (DDB: 34)
Input L4 (DDB: 35)
The Aided 1 Scheme RX signal corresponds to a 'channel-receive' signal for scheme 1. The Aided 1 COS/LGS signal
corresponds to a 'channel out of service' or 'loss of guard' signal ('Loss of guard' is the inverse signal to 'guard
received').
As well as the default mapping, it is possible to map the signals to other inputs if required.
The window during which the unblocking logic is enabled starts 10ms after the guard signal is lost and continues
for 150ms. The 10ms delay gives time for the signalling equipment to change frequency.
Note:
If the Z1 Ext Scheme setting is set to operate for channel failure, the Zone 1 extension logic will be invoked if a channel failure
is detected.
This scheme type also provides Loss of Guard logic as described below.
System condition
channel received
Healthy Line No
Internal Line Fault Yes
Unblock No
Signalling Anomaly Yes
P54x1i-TM-EN-1
Permissive
Loss of guard
No
Yes
Yes
No
Aided 1 Scheme Rx (DDB: 493)
Aided 1 COS/LGS (DDB: 492)
Permissive
trip allowed
No
Yes
Yes, during a 150 ms window
No
Chapter 8 - Carrier Aided Schemes
DDB signal
Alarm
generated
No
No
Yes, delayed on pickup by 150 ms
Yes, delayed on pickup by 150 ms
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