ABB 615 Series - Standard Inverse-Time Characteristics

11.2.1.1 Standard inverse-time characteristics
For inverse-time operation, both IEC and ANSI/IEEE standardized inverse-time
characteristics are supported.
The trip times for the ANSI and IEC IDMT curves are defined with the coefficients A, B
and C.
The values of the coefficients can be calculated according to the formula:
t s
A
I
I
B k
c
[ ] =
>






−
+














⋅
1
A060821 V2 EN (Equation 173)
t[s] t[s] = Trip time in seconds
I measured current
I> set Pickup value
k set Time multiplier
Table 943: Curve parameters for ANSI and IEC IDMT curves
Curve name
A B C
(1) ANSI Extremely
Inverse
28.2 0.1217 2.0
(2) ANSI Very Inverse 19.61 0.491 2.0
(3) ANSI Normal Inverse 0.0086 0.0185 0.02
(4) ANSI Moderately
Inverse
0.0515 0.1140 0.02
(6) Long Time Extremely
Inverse
64.07 0.250 2.0
(7) Long Time Very
Inverse
28.55 0.712 2.0
(8) Long Time Inverse 0.086 0.185 0.02
(9) IEC Normal Inverse 0.14 0.0 0.02
(10) IEC Very Inverse 13.5 0.0 1.0
(11) IEC Inverse 0.14 0.0 0.02
Table continues on next page
Section 11 1MAC059074-MB A
General function block features
1082 615 series ANSI
Technical Manual