IM30-DK
Doc. N° MO-0040-ING
Rev.
2
Pag.
12
of
34
Copyright 2010 - Microener
Example:
-
C/B rated current = 630A
-
CT rated current = 500A
-
Number of conventional interruptions that the C/B can perform before maintenance is needed
NWc=500
The relay variables are set accordingly:
500Wc
Wi
1.26;
500
630
Ii
An interruption with current, for example, 2000A produces an accumulation
10Wc
630
2000
2
2
.
When the summation of the accumulations exceeds the set limit Wi = 500Wc the maintenance alarm is
issued.
In the menu “TRIPNUM” exists a measurement “%Wi” that, at any interruption, is decremented by the
amount of energy relevant to th
e interruption computed as % of the value set for “Wi”.
In the above example, the accumulation relevant to the interruption of 2000A was 10Wc corresponding
to:
Wi
2%
100
500
10
This 2% is subtracted from the existing measurement “%Wi” so that the actual value “%Wi” shows the
percent of the C/B utilization still remaining before maintenance is needed.
