Areva MiCOM P441, Technical Manual

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P44x/EN AP/E33 Application Notes
Page 154/220 MiCOM P441/P442 & P444
Where ‘None’ is selected no CB status will be available. This will directly affect any function
within the relay that requires this signal, for example CB control, auto-reclose, etc. Where
only 52a is used on its own then the relay will assume a 52b signal from the absence of the
52a signal. Circuit breaker status information will be available in this case but no discrepancy
alarm will be available. The above is also true where only a 52b is used. If both 52a and 52b
are used then status information will be available and in addition a discrepancy alarm will be
possible, according to the following table. 52a and 52b inputs are assigned to relay opto-
isolated inputs via the PSL.
Auxiliary Contact Position CB State Detected Action
52a 52b
Open Closed Breaker Open Circuit breaker healthy
Closed Open Breaker Closed Circuit breaker healthy
Closed Closed CB Failure Alarm raised if the condition
persists for greater than 5s
Open Open State Unknown Alarm raised if the condition
persists for greater than 5s
Where single pole tripping is used (available on P442 and P444) then an open breaker
condition will only be given if all three phases indicate and open condition. Similarly for a
closed breaker condition indication that all three phases are closed must be given. For single
pole tripping applications 52a-A, 52a-B and 52a-C and/or 52b-A, 52b-B and 52b-C inputs
should be used.
With 52a&52b both present, the relay memorizes the last valid status of the 2 inputs
(52a=/52b). If no valid status is present (52a=52b) when the Alarm timer is issued
(value=150 msec), CBA_Status Alarm is activated. See Figure 109.