ABB RER620 Technical Manual page 472

Section 10
General function block features
466
⎛ ⎞
⎜ ⎟
A
⎜ ⎟
[ ] = + ⋅
t s B k
⎜ ⎟
c
I
⎛ ⎞
⎜ ⎟
⎟ −
1
⎜
⎜ ⎟
>
I
⎝ ⎠
⎝ ⎠
t[s] t[s] = Trip time in seconds
I measured current
set Pickup value
I>
set Time multiplier
k
Table 421: 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
(12) IEC Extremely Inverse
(13) IEC Short Time Inverse
(14) IEC Long Time Inverse
The maximum guaranteed measured current is 50 x In for the current
protection. When the set Pickup value exceeds 1.00 x In, the turn point
where the theoretical IDMT characteristics are leveling out to the definite
time can be calculated with the formula:
Turn point
50× In
=
Pickupvalue
1MAC309294-MB F
(Equation 57)
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
80.0 0.0
0.05 0.0
120 0.0
(Equation 58)
Technical Manual
C
2.0
2.0
0.02
0.02
2.0
2.0
0.02
0.02
1.0
0.02
2.0
0.04
1.0
RER620