ISA T1000 PLUS - Page 141

DOC. MIE91093 Rev. 1.34 Page 141 of 145
IEEE - US Inverse
29.75
0.9
2
IEEE - US Short Inverse
0.0171
0.0131
0.02
With IAC and ANSI standards, the different curves correspond
to the following formula.
c
I
I
e
c
I
I
d
c
I
I
b
a* K ) s (t
3
R
2
R
R
T












































Constants of the formula change according to the type of
curve; they are summarised in the following table.
IAC, ANSI
a
b
c
d
e
IAC Inverse
0.2078
0.863
0.8
-0.418
0.1947
IAC Short Time
Inverse
0.0428
0.0609
0.62
-0.001
0.0221
IAC Long Time
Inverse
80
0
2
2
2
IAC Very
Inverse
0.09
0.7955
0.1
-1.2855
7.9586
IEC Extremely
Inverse
0.004
0.6379
0.62
1.7872
0.2461
ANSI -
Extremely
Inverse
0.0399
0.2294
0.5
3.0094
0.7222
ANSI - Very
Inverse
0.0615
0.7989
0.34
-0.284
4.0505
ANSI - Normal
Inverse
0.0274
2.2614
0.3
-4.1899
9.1272
ANSI -
Moderately
Inverse
0.1735
0.6791
0.8
-0.08
0.1271