P54x/EN OP/La4 Operation
(OP) 5-170
MiCOM P543, P544, P545 & P546
OP
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 “CB
Status time”
Open Open State Unknown
Alarm raised if the condition
persists for greater than “CB
Status time”
In the internal logic of the P544/P546, the breaker position used in the algorithm is
considered to be open when the CB State Detected is Breaker Open. In all others cases,
the breaker position is considered to be closed. Therefore, during operation of the circuit
breaker, if the condition 52A=52B=0 or 52A=52B=1 is encountered, the circuit breaker is
considered to be closed.
Where single pole tripping is used, then an open breaker condition will only be given if all
three phases indicate an 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 circuit breaker
state monitoring logic diagrams for CB1 & CB2 are shown in AR Figure 1 and Figure 2 (logic
diagram supp
lement).
If inputs relevant to each of the circuit breakers (CB1 and CB2) are available to the relay via
the opto isolated inputs, the logic will be able to determine the state of each circuit breaker.
5.4 Circuit breaker condition monitoring
(P544/P546)
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. The circuit breaker monitoring features of the P544/P546 can help with more
efficient maintenance regimes.
5.4.1 Circuit breaker condition monitoring features (P544/P546)
For ea
ch trip operation for each circuit breaker the relay records statistics as shown in the
following table taken from the relay menu. The menu cells shown are counter values only.
The Min./Max. values in this case show the range of the counter values. These cells can not
be set.
Setting
Menu text Default
Min. Max.
Step size
CB1 A Operations 0 0 10000 1
Displays the total number of A phase trips issued by the relay for CB1.
CB1 B Operations 0 0 10000 1
Displays the total number of B phase trips issued by the relay for CB1.
CB1 C Operations 0 0 10000 1
Displays the total number of C phase trips issued by the relay for CB1.
CB1 A Broken
0 0
25000 n^
1
Displays the total fault current interrupted by the relay for the A phase for CB1.
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