Thytronic SIF5600 - 8.1 APPENDIX A1 - INVERSE TIME IEC CURVES; Residual Overcurrent 50 N51 N - Extremely Inverse Time Curve (IEC 60255-3 BS142 Type C)

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SIF5600 - Manual - 03 - 2008
Residual overcurrent 50N/51N - Extremely inverse time curve (IEC 60255-3/BS142 type C)
t =
t
E
>
dep
·
[(I
E
/I
E
>
dep
)
2
-1]
K
1.1
2 3 4 5 6 7 8 9 10 20
I
E
/I
E
>
dep
0.01
0.1
1
10
100
1000
10000
100000
t [s]
t
E
>
dep
= 10.0 s
t
E
>
dep
= 60.0 s
t
E
>
dep
= 30.0 s
t
E
>
dep
= 5.00 s
t
E
>
dep
= 1.00 s
t
E
>
dep
= 0.50 s
t
E
>
dep
= 0.30 s
t
E
>
inv
= 0.10 s
Note: match of operating and setting time takes place when:
I
E
/I
E
>
dep
= 4 for 2.00 fw release (SIF5600-Manual-10-2006” reference document)
I
E
/I
E
>
dep
= 9 for 2.10 and following fw releases
K = 15 for 2.00 fw release
K = 80 for 2.10 and following fw releases