Standard Inverse-Time Characteristics - ABB 615 series Technical Manual

Section 11
General function block features
11.2.1.1
1082

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:
 
 
A
 
t s [ ] = B k
+ ⋅
 c 
I
 
 
1
 −

 
I
>
 
 
A060821 V2 EN
t[s] t[s] = Trip time in seconds
I measured current
I> set Pickup value
Time multiplier
k set
Table 943: Curve parameters for ANSI and IEC IDMT curves
Curve name
(1) ANSI Extremely
Inverse
(2) ANSI Very Inverse
(3) ANSI Normal Inverse
(4) ANSI Moderately
Inverse
(6) Long Time Extremely
Inverse
(7) Long Time Very
Inverse
(8) Long Time Inverse
(9) IEC Normal Inverse
(10) IEC Very Inverse
(11) IEC Inverse
Table continues on next page
A B
28.2 0.1217
19.61 0.491
0.0086 0.0185
0.0515 0.1140
64.07 0.250
28.55 0.712
0.086 0.185
0.14 0.0
13.5 0.0
0.14 0.0
1MAC059074-MB A
(Equation 173)
C
2.0
2.0
0.02
0.02
2.0
2.0
0.02
0.02
1.0
0.02
615 series ANSI
Technical Manual