19
4
Rated and setting currents
In = rated current of current transformer
I> = setting value of overload current (51)
I>> = setting value of short-circuit current (50)
Io> = setting value of earth fault current (first threshold) (51N)
Io>> = setting value of earth fault current (second threshold) (50N)
(1) If an external toroidal current transformer is used, recalculate the setting values according to its primary
rated current.
Current Protection functions
transformer (CT)
In I> I>> Io> Io>>
[A] 0.2 ... 1 x In [A] 2.5 ... 20 x I> [A] 0.1 ... 1 x In [A]
(1)
2.5 ... 20 x Io> [A]
(1)
40 8 ... 40 20 ... 800 4 ... 40 10 ... 800
80 16 ... 80 40 ... 1600 8 ... 80 20 ... 1600
100 20 ... 100 50 ... 2000 10 ... 100 25 ... 2000
150 30 ... 150 75 ... 3000 15 ... 150 37.5 ... 3000
200 40 ... 200 100 ... 4000 20 ... 200 50 ... 4000
250 50 ... 250 125 ... 5000 25 ... 250 62.5 ... 5000
600 120 ... 600 300 ... 12000 60 ... 600 150 ... 12000
1250 250 ... 1250 625 ... 25000 125 ... 1250 32.5 ... 25000
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