ISA T1000 PLUS - Page 142

DOC. MIE91093 Rev. 1.34 Page 142 of 145
With US standards, the different curves correspond to the
following formula.
























1
c
I
I
b
a*K ) s (t
R
T
Constants of the formula change according to the type of
curve; they are summarised in the following table.
US
a
c
b
US Moderately Inverse
0.0226
0.0104
0.02
US Inverse
0.18
5.95
2
US Very Inverse
0.0963
3.88
2
US Extremely Inverse
0.0352
5.67
2