Areva MiCOM P441, Technical Manual

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P44x/EN AP/E33 Application Notes
Page 52/220 MiCOM P441/P442 & P444
2.9.4.3 Loss of Carrier
In this mode the signalling equipment used is such that a carrier/data messages are
continuously transmitted across the channel, when in service. For a permissive trip signal to
be sent, additional information is contained in the carrier (eg. a trip bit is set), such that both
the carrier and permissive trip are normally received together. Should the carrier be lost at
any time, the relay must open the unblocking window, in case a line fault has also affected
the signalling channel. Two opto inputs to the relay need to be assigned, one is the Channel
Receive opto, the second is designated Loss of Carrier (the inverse function to carrier
received). The function logic is summarised in Table 4.
System
Condition Permissive
Channel
Received Loss of
Guard Permissive Trip
Allowed Alarm
Generated
Healthy Line No No No No
Internal Line Fault Yes No Yes No
Unblock No Yes Yes, during a
150ms window Yes, delayed on
pickup by 150ms
Signalling
Anomaly No Yes No Yes, delayed on
pickup by 150ms
TABLE 4 - LOGIC FOR THE LOSS OF CARRIER FUNCTION
The window of time during which the unblocking logic is enabled starts 10ms after the guard
signal is lost, and continues for 150ms.
For the duration of any alarm condition, zone 1 extension logic will be invoked if the option
Z1 Ext on Chan. Fail has been Enabled.
P3062ENa
10 ms
&
Pulse Timer
150 ms
150 ms
Pulse Timer
200 ms
≥
1
UNB Alarm
INP COS
Indicates by digital input
the Loss of Carrier
INP CR
UNB CR
S
0
0
Q
R
S
Q
R
&
FIGURE 29 - LOSS OF CARRIER