Alstom MiCOM P545 - 4.5 Circuit breaker condition monitoring (P543;P545)

P54x/EN OP/La4 Operation
(OP) 5-158 MiCOM P543, P544, P545 & P546
OP
If any of the above conditions exist, an alarm will be issued after a 5s time delay. 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.
In the CB CONTROL column of the relay menu there is a setting called ‘CB Status Input’.
This cell can be set at one of the following seven options:
None
52A 3 pole
52B 3 pole
52A & 52B 3 pole
52A 1 pole
52B 1 pole
52A & 52B 1 pole
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 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. The CB state
monitoring logic is shown in AR Figure 1.
4.5 Circuit breaker condition monitoring (P543/P545
)
Periodic maintenance of circuit breakers is necessary to ensure that the trip circuit and
mechanism operate correctly, and also that the interrupting capability has not been
compromised due to previous fault interruptions. Generally, such maintenance is based on a
fixed time interval, or a fixed number of fault current interruptions. These methods of
monitoring circuit breaker condition give a rough guide only and can lead to excessive
maintenance.
If inputs relevant to the circuit breakers are available to the relay via the opto isolated inputs,
the logic will be able to determine the state of each circuit breaker.