Alstom MiCOM P545 - 5.3 Circuit breaker status (P544;P546)

Operation P54x/EN OP/La4
MiCOM P543, P544, P545 & P546 (OP) 5-169
OP
5.3 Circuit breaker status (P544/P546)
For each circuit breaker, the P544/P546 incorporates circuit breaker state monitoring, giving
an indication of the position of each circuit breaker or, if the state is unknown, an alarm is
raised.
The P544/P546 can be set to monitor normally open (52A) and normally closed (52B)
auxiliary contacts of each circuit breaker. For each circuit breaker, under healthy conditions,
the 52A and 52B contacts should be in opposite states. Should both sets of contacts be
open, this would indicate one of the following conditions:
 Auxiliary contacts/wiring defective
 Circuit breaker is defective
 Circuit breaker is in an isolated position
Should both sets of contacts be closed, only one of the following two conditions would apply:
 Auxiliary contacts/wiring defective
 Circuit Breaker is defective
If any of the above conditions exist, an alarm will be issued after time delay as set in CB
Status time in the CB CONTROL settings column of the menu. A normally open / normally
closed output contact can be assigned to this function via the programmable scheme logic
(PSL). The time delay is set to avoid unwanted operation during normal switching duties
where fleeting abnormal circuit breaker status conditions may exist as the contacts change
state.
Note: The CB Status time setting is one setting applied equally to both
controlled circuit breakers.
In the CB CONTROL column of the relay menu there are two settings: CB1 Status Input
and CB2 Status Input. Each cell can be set at one of the following seven options to control
CB1 and/or CB2:
None
52A 3 pole
52B 3 pole
52A & 52B 3 pole
52A 1 pole
52B 1 pole
52A & 52B 1 pole
If None is selected, no circuit breaker status will be available. This will directly affect any
function within the relay that requires this signal, for example circuit breaker control,
auto-reclose, etc..
Where only 52A (open when the circuit breaker is open, closed when the circuit breaker is
closed) is used 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 (closed when the circuit breaker is
open, open when the circuit breaker is closed) is used.
If both 52A and 52B are used then status information will be available and in addition a
discrepancy alarm CBx Status Alarm (x = 1 or 2) will be possible, according to the following
table. 52A and 52B inputs are assigned to relay opto-isolated inputs via the PSL.