
APPENDIX
143
NA20 - Manual - 04 - 2022
Negative sequence overcurrent 46 - Standard inverse time curve (IEC 60255-3/BS142 type A)
F_46-IECA-Char.ai
1.1
2
3
4
5
6 7 8 9 10
20
I
2
/I
2
>
inv
0.01
0.1
1
10
100
1000
10000
t
[s]
t
2
>
inv
= 60 s
t
2
>
inv
= 10 s
t
2
>
inv
= 5 s
t
2
>
inv
= 1 s
t
2
>
inv
= 0.5 s
t
2
>
inv
= 0.2 s
t
2
>
inv
= 0.1 s
t
2
>
inv
= 0.02 s
t
=
t
2
>
inv
·
[(
I
2
/
I
2
>
inv
)
0.02
-1]
0.14
Note: match of operating and setting time takes place when I
2
/I
2
>
inv
= 700
Содержание NA20
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