ABB Relion 670 series - Page 269

I
G
ground current of faulty line
K
N
is ground compensation factor for single circuit set at the relay given
by equation
0 1
1
3
N
Z Z
K
Z
=
-
×
IECEQUATION14005 V1 EN (Equation 162)
The short circuit voltage can be calculated as:
V Z
Z Z
I
Z
I Z I
Z Z
Z
I
Z
Z
I
ph ph G
m
Gp ph G
m
G
I= ⋅ +
−
⋅ + ⋅ = +
−
⋅ + ⋅
1
0 1 0
1
0 1
1
0
1
3 3 3 3
(
pp
)
ANSIEQUATION14006 V2 EN (Equation 163)
Where I
Ep
is the ground current in the parallel line.
As explained above, the distance relay phase-to-ground measures:
Z
V
I K I
ph
ph N G
=
+ ⋅
ANSIEQUATION14004 V2 EN (Equation 164)
Z
V
I K I
Z
I
Z Z
Z
I
Z
Z
I
I K I
ph
ph n G
ph G
m
Gp
ph n G
=
+ ⋅
= ⋅
+
−
⋅ + ⋅
+ ⋅
1
0 1
1
0
1
3 3
ANSIEQUATION14007 V2 EN (Equation 165)
Taking earth compensation factor
0 1
1
3
N
Z Z
K
Z
-
=
for single circuit and
0
1
3
m
Nm
Z
K
Z
=
impedance measured by distance relay can be written as:
Z Z
K I
I K I
Nm Gp
ph N G
= +
⋅
+ ⋅








1
1
ANSIEQUATION14010 V1 EN (Equation 166)
1MRK 506 369-UUS - Section 8
Impedance protection
Line distance protection REL670 2.2 ANSI 263
Application manual