366
NVA100X-D - Manual - 02 - 2016
APPENDIX
Ground directional overcurrent 67N(Comp) - Electromechanical inverse curves (EM)
—
F_67N-EM-Char.ai
1.1
2
3
4
5
6
7
8 9 10
20
0.01
0.1
1
10
100
1000
10000
t
[s]
I
EDC
/
I
EDH
>inv
I
EDC
/
I
EDH
>>inv
I
EDC
/
I
EDL
>inv
I
EDC
/
I
EDL
>>inv
0.1 s
0.02 s
10 s
5 s
1 s
0.5 s
0.2 s
60 s
Note: match of operating and setting time takes place when I
EDC
/I
EDH
>
inv
= 4 or I
EDC
/I
EDH
>>
inv
= 4
t
=
t
EDC
>
inv
t
EDC
>
inv
·
[-0.236
·
(
I
EDC
/
I
EDH
>
inv
)
-1
+ 0.339]
0.28
t
=
t
EDC
>
inv
·
[-0.236
·
(
I
EDC
/
I
EDL
>
inv
)
-1
+ 0.339]
0.28
t
=
t
EDC
>>
inv
·
[-0.236
·
(
I
EDC
/
I
EDH
>>
inv
)
-1
+ 0.339]
0.28
t
=
t
EDC
>>
inv
t
EDC
>>
inv
·
[-0.236
·
(
I
EDC
/
I
EDL
>>
inv
)
-1
+ 0.339]
0.28