ABB SPAC 531 C User Manual And Technical Description page 116

Inverse-time
characteristics of
overcurrent relay
module SPCJ 3C3.
14
t/s
70
60
50
40
30
20
10
9
8
7
6
5
4
3
2
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
1
Fig. 3. Extremely inverse characteristic.
I = measured current
I> = set start current
t = operation time
k = time multiplier
2 3 6 7 8 9 10
4 5
k
1.0
0.8
0.6
0.4
0.3
0.2
0.1
0.05
20 I/I>