Curve Networks with isolated neutral point.Page 27
Applications
If detuning specified percentage, the expected reactive current across the faulty
section calculated according the following formula
( )
100
res fix
v
I v
I
(1. 130 A). Ires equal the
grid's capacitive current, when earth fault occurs
Ifix Current connected fixed coil grid
v Detuning %
In very large grids, the values recommended VDE 0228 Part for the self-extinguishing
current limit may exceeded (up kV: 110 ca.24)
Iv Detuning current (reactive current A
Ires Current through the adjustable P-coil the resonance point. This curve also applies cable networks with to
20 nominal voltage with small component overhead cables even their
neutral point isolated.
Figure 11: Self-extinguishing current limit accordance with VDE 0228, Part 2
Curve Self-extinguishing current limit for earth-fault residual current for grids with
earth-fault compensation.
nominal voltage
earth
fault
curren
t
