
2.14 Fault Locator
153
7ST6 Manual
E50417-G1176-C251-A3
Figure 2-42
Determination of the distance to fault from the calculated fault reactance
As a result, the fault location works correctly even if there are line sections with differ-
ent reactance per unit length characteristics, or transformers, between the protection
device and the fault.
Note
The precision of the fault locator specified in the Technical Data applies to faults with
a sufficiently long measuring window for calculating the fault location. In case of an in-
stantaneous trip, the precision of the fault location is necessarily reduced due to the
short fault clearance time and the high harmonics content in the measured current and
voltage signals.
Output of the Fault
Location
The fault locator issues the following results:
• Fault direction (forward / reverse)
• Reactance X in
Ω
primary and
Ω
secondary,
• Resistance R in
Ω
primary and
Ω
secondary,
• Distance to fault d in kilometres or miles, calculated on the basis of the reactance
per unit length characteristics parameterized for the line sections,
• Distance to fault d in % of the line length.
Note
If the function fault locator is available, the determination of the direction, apart from
the distance protection, can also be executed by the fault locator. The results of both
procedures may differ in rare cases. The direction determination of the fault locator
can be more precise due to the longer measuring window.
www
. ElectricalPartManuals
. com