GE P444

Application Notes
P44x/EN AP/Hb
6
MiCOM P40 Agile P442, P444
(AP) 5-
165
Sol6: Six opto inputs used for 52a &52b (1-pole cicuit breaker)
Figure 133: Different opto inputs / CB aux schemes (cont’d)
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 and 52b both present, the relay stores in memory the last valid state of the 2 inputs
(52a=/52b). If no valid state is present (52a=52b) on expiry of the Alarm time-delay
(value=150ms), the CB Status Alarm is issued.