Rockwell Automation 865 Differential Protection Relay - Manual (Page 99)

Supporting Functions 4-7
865-UM001A-EN-P – July 2009
The points 4...8 are not needed for the CB in Figure 4.1. Thus
they are set to 100 kA and one operation in the table to be
discarded by the algorithm.
10
20
50
100
1000
10000
100000
100 200 500 1000 10000 100000
Number
of
permitted
operations
Breaked current (A) CBWEARcharacteristics
Figure 4.1 – An example of circuit breaker wearing characteristic graph
Table 4.7 – Example of Circuit Breaker Wearing Characteristics
Point Interrupted current (kA) Number of permitted operations
1 0 (mechanical age) 10000
2 1.25 (rated current) 10000
3 31.0 (maximum breaking current) 80
4 100 1
5 100 1
6 100 1
7 100 1
8 100 1
Note: Values taken from Figure 4.1. The table is edited with SetPointPS under menu
“Breaker Curve”.
Setting Alarm Points
There are two alarm points available having two setting parameters
each.
Current
The first alarm can be set for example to nominal current of the
CB or any application typical current. The second alarm can be
set for example according a typical fault current.
Operations left alarm limit
An alarm is activated when there are less operation left at the
given current level than this limit.