147
6
F
2
S
0
8
3
4
X1 = reactance component of line positive sequence impedance
Kbc = impedance imbalance compensation factor
Im( ) = imaginary part in parentheses
Re( ) = real part in parentheses
L = line length (km)
Distance calculation for earth fault (in the case of A-phase earth fault)
x
1
=
I
m
(V
a
⋅
I
α
")
×
L
{I
m
(R
1
⋅
I
α
⋅
I
α
" + R
0
⋅
I
0S
⋅
I
α
" + R
0m
⋅
I
0m
⋅
I
α
") + R
e
(X
1
⋅
I
α
⋅
I
α
" + X
0
⋅
I
0S
⋅
I
α
" + X
0m
⋅
I
0m
⋅
I
α
")}
×
K
a
where,
Va = fault voltage
I
α
= fault current = (2Ia
−
Ib
−
Ic)/3
I
α
" = change of fault current before and after fault occurrence
=
2Ia
−
Ib
−
Ic
3
−
2ILa
−
ILb
−
ILc
3
Ia, Ib, Ic = fault current
ILa, ILb, ILc = load current
I0s = zero sequence current
I0m = zero sequence current of parallel line
R1 = resistance component of line positive sequence impedance
X1 = reactance component of line positive sequence impedance
R0 = resistance component of line zero sequence impedance
X0 = reactance component of line zero sequence impedance
R0m = resistance component of line mutual zero sequence impedance
X0m = reactance component of line mutual zero sequence impedance
Ka = impedance imbalance compensation factor
Im( ) = imaginary part in parentheses
Re( ) = real part in parentheses
L = line length (km)
Equations (1) and (2) are general expressions when lines are treated as having lumped constants
and these expressions are sufficient for lines within 100 km. For lines exceeding 100 km,
influences of the distributed capacitance must be considered. For this fault locator, the following
equation is used irrespective of line length to find the compensated distance
x
2
with respect to
distance
x
1
which was obtained in equation (1) or (2).
x
2
=
x
1
−
k
2
⋅
x
1
3
3 (3)
where,
k = propagation constant of the protected line = 0.001km
-1
(fixed)
(2)
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. ElectricalPartManuals
. com
Summary of Contents for GRZ100-211B
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