*2Inom
del
[
s
]
IDMT curve shape selection.
2Inom del
is Reaction time of IDMT protection for 200% overcurrent
Igen = 2*
Nominal current
.
Step:
0,1
s
Range:
0,1 - 20 s
IDMT is “very inverse” generator over current protection. Reaction time is not constant but depends on
generator over current level according following formula.
2Inom del * Nomin current
Reaction time =
Igen
-
Nomin current
Hint:
Reaction time is limited up to 900 sec = 15 minutes. IDMT protection is not active for Reaction time
values longer than 15 minutes.
Igen is maximal value of all measured phases of generator current.
EXAMPLE of Reaction time for different over current levels. Values in column 200% are
2Inom del.
Overcurrent
200 % =
2Inom del
≤
100 %
101 %
110 %
0,2 s
No action
20 s
2 s
2 s
No action
200 s
20 s
Reaction time
20 s
No action
No action
(time > 900 s)
200 s
Igen
Nominal current
Ishort
2Inom del
Maximal Reaction time
R
e
a
c
tio
n
tim
e
InteliLite – MRS10/11/15/16, SW version 2.2, ©ComAp – November 2004 34
IL-MRS-2.2.pdf