ABB RELION REF615R, Technical Manual

Page: 583 / 664

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 33)
t[s] t[s] = Trip time in seconds
I
measured current
I> set Pickup value
k set Time multiplier
Table 438: 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
(12) IEC Extremely
Inverse
80.0 0.0 2.0
(13) IEC Short Time
Inverse
0.05 0.0 0.04
(14) IEC Long Time
Inverse
120 0.0 1.0
1MRS240050-IB C
Section 12
General function block features
REF615R 577
Technical Manual