14) simplified to:
1
U
Res N
U W
Y
U U
Y Y
(1.17)
There, based the assumption that YW, the following equation applies the corre-
sponding coil position Ipos,W=BL,WU1N.16)
In order understand IW, have take look the point the resonance curve
where:
1
2
NE
Res
U
U
(1.Page 23
Applications
Continuing from the previous chapter, Figure shows the progression the absolute val-
ue the zero sequence voltage UNE based the coil position (Ipos=BLU1N).
At the resonance point (BC=BL), equation (1.
These three parameters are easily determined from the resonance curve. Figure shows
the corresponding locus (absolute value and phase) based the coil position.18)
Multiplying expression
.
, ,
1 1
( )
2 1
ne
C W
res
U W
U
j B
U
Y Y
(1.
Figure Locus zero sequence voltage UNE
The resonance curve healthy grid can described the following parameters:
Ures Maximum zero sequence voltage
Ires Coil position Ipos Ures point; corresponds the momentary grid capacitance ICE
Iw Expected watt-metric current across the faulty section, when low impedance
earth fault occurs
