Siemens SIPROTEC 7SJ62 Manual page 57

For ground impedance ratios, the following results:
Reactance per Unit Length (only for Fault Location)
The setting of the reactance per unit length is only important for the utilization of the line fault location function.
The reactance setting enables the protective relay to indicate the fault location in terms of distance.
The reactance value X' is entered as a reference value x', i.e. in Ω/mile if set to distance unit Miles (address
215, see Section 2.1.3.2 under "Distance Unit") or in Ω/km if set to distance unit km. If, after having entered the
reactance per unit length, the distance unit is changed under address 215, the reactance per unit length must
be reconfigured in accordance with the new distance unit.
The values under address 1106 (km) or 1105 (Miles) apply if only one line section is available and to all faults
that occur outside the defined line sections.
If several line sections are set, the following shall apply:
• for line section 1, addresses 6004(km) or 6003 (Miles)
• for line section 2, addresses 6014(km) or 6013 (Miles)
• for line section 3, addresses 6024 (km) or 6023 (Miles).
When setting the parameters in DIGSI, the values can also be entered as primary values. In that case the fol-
lowing conversion to secondary values is not required.
For the conversion of primary values to secondary values the following applies in general:
Likewise, the following applies to the reactance per unit length of a line:
with
N
CTR
N
VTR
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
– Transformation ratio of the current transformer
– Transformation ratio of the voltage transformer
Functions
2.1 General
57