
APPENDIX
149
NA20 - Manual - 04 - 2022
Phase overcurrent 50/51 - long time inverse curve (IEC BS B LI)
F_51-IEC-LTI-Char.ai
t
=
t
>
inv
·
[(
I
/
I
>
inv
) -1]
120
Note: match of operating and setting time takes place when I/I>
inv
= 121
0.01
0.1
1
10
100
1000
10000
t
[s]
1.1
2
3
4
5
6 7 8 9 10
20
I
/
I
>inv
t
>
inv
= 60 s
t
>
inv
= 10 s
t
>
inv
= 5.0 s
t
>
inv
= 1.0 s
t
>
inv
= 0.5 s
t
>
inv
= 0.2 s
t
>
inv
= 0.1 s
t
>
inv
= 0.02 s
Содержание NA20
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