APPENDIX
170
NA30 - Manual - 04 - 2022
Ground directional overcurrent 67N - Extremely inverse time curve (IEC 60255-3/BS142 type C)
F_67-IECC-Char.ai
1.1
2
3
4
5
6 7 8 9 10
20
I
ED
/
I
ED
>inv
I
ED
/
I
ED
>>inv
0.01
0.1
1
10
100
1000
10000
100000
t
[s]
t
ED
>
inv
= 10 s
t
ED
>
inv
= 10 s
t
ED
>
inv
= 60 s
t
ED
>>
inv
= 60 s
t
ED
>
inv
= 5 s
t
ED
>
inv
= 5 s
t
ED
>
inv
= 1 s
t
ED
>
inv
= 1 s
t
ED
>
inv
= 0.5 s
t
ED
>>
inv
= 0.5 s
t
ED
>
inv
= 0.2 s
t
ED
>>
inv
= 0.2 s
t
ED
>
inv
= 0.02 s
t
ED
>>
inv
= 0.02 s
t
ED
>
inv
= 0.1 s
t
ED
>>
inv
= 0.1 s
Note: match of operating and setting time takes place when I
ED
/I
ED
>
inv
= 9 or I
ED
/I
ED
>>
inv
= 9
t
=
t
ED
>>
inv
·
[(
I
ED
/
I
ED
>>
inv
)
2
-1]
80
t
=
t
ED
>
inv
·
[(
I
ED
/
I
ED
>
inv
)
2
-1]
80