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Note
When the addresses 1116 RE/RL(Z1) and 1118 RE/RL(> Z1) are set to about 2.0 or more, please keep in
mind that the zone reach in R direction should not be set higher than the value determined previously (see
Section 2.5.2.2/margin heading Resistance Tolerance). If this is not observed, it may happen that phase-to-
earth impedance loops are measured in an incorrect distance zone, which may lead to loss of tripping coordi-
nation in the case of earth faults with fault resistances.
Earth Impedance (Residual) Compensation with Magnitude and Angle (K
When the complex earth impedance (residual) compensation factor K
apply. In this case it is important that the line angle is set correctly (address 1105, see margin heading „General
Line Data") as the device needs the line angle to calculate the compensation components from the K
earth impedance compensation factors are defined with their magnitude and angle which may be calculated
with the line data using the following equation:
Where
Z
0
Z
1
These values can be applied either to the entire line or as per unit of length values since the quotients are in-
dependent of length. Furthermore, it makes no difference whether the quotients are calculated with primary, or
secondary values.
For overhead lines it is generally possible to calculate with scalar quantities as the angle of the zero sequence
and positive sequence system only differ by an insignificant amount. With cables however, significant angle dif-
ferences may exist as illustrated by the following example.
Calculation Example:
110 kV single-conductor oil-filled cable 3 · 185 mm
Z
/s
1
Z
/s
0
(where s
The calculation of the earth impedance (residual) compensation factor K
The magnitude of K
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
= (complex) zero sequence impedance of the line
= (complex) positive sequence impedance of the line
j73°
= 0.408 · e
Ω/km positive sequence impedance
j18.4°
= 0.632 · e
Ω/km zero sequence impedance
= line length)
is therefore
0
–Factor)
0
is set, the addresses 1120 to 1123
0
2
Cu with the following data
results in:
0
Functions
2.1 General
. These
0
61
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