Thytronic NA30

APPENDIX
180
NA30 - Manual - 04 - 2022
 Ground directional overcurrent 67N - Extremely inverse time curve (ANSI/IEEE type EI)
F_67N-ANSIEI-Char.ai
1.1
2 3 4 5 6 7 8 9 10 20
I
ED
/I
ED
>inv
0.01
0.1
1
10
100
1000
10000
t [s]
t
ED
>
inv
= 10 s
t
ED
>
inv
= 60 s
t
ED
>
inv
= 5 s
t
ED
>
inv
= 0.5 s
t
ED
>
inv
= 1 s
t
ED
>
inv
= 0.2 s
t
ED
>
inv
= 0.1 s
t
ED
>
inv
= 0.02 s
t =
t
ED
>
inv
·
[(I
ED
/I
ED
>
inv
)
2
-1]
5.64
+ 0.024
Note: match of operating and setting time takes place when I
ED
/I
ED
>
inv
= 2.789