Thytronic NC020 - Phase Overcurrent 50;51 - Extremely Inverse Time Curve (ANSI;IEEE Type EI)

APPENDIX
78
NC020 - Manual - 05 - 2022
— Phase overcurrent 50/51 - Extremely inverse time curve (ANSI/IEEE type EI)
F_51-ANSIEI-Char.ai
1.1
2 3 4 5 6 7 8 9 10 20
I /I>>
inv
I
RMS
/I>
inv
0.01
0.1
1
10
100
1000
10000
t [s]
10 s
60 s
t>
inv
t>>
inv
5 s
0.5 s
1 s
0.2 s
0.1 s
0.02 s
t =
t>
inv
·
[(I
RMS
/I>
inv
)
2
-1]
5.64
+ 0.024
t =
t>>
inv
·
[(I /I>>
inv
)
2
-1]
5.64
+ 0.024
Note: match of operating and setting time takes place when I
RMS
/I>
inv
= 2.789