Functions
2.21 Fault Locator
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
391
Figure 2-182 Fault currents and voltages on double–end fed lines
M : Measuring point
E1, E2 : Source voltage (EMF)
IF1, IF2 : Partial fault currents
IF1 + IF2 : Total fault current
UF1 : Fault voltage at the measuring point
RF : Common fault resistance
ZF1, ZF2 : Fault impedances
ZF1E, ZF2E : Earth fault impedances
ZS1, ZS2 : Source impedances
ZS1E, ZS2E : Earth source impedances
2.21.2 Setting Notes
General
The fault location function is only in service if it was set to Enabled during the configuration of the device func-
tions (Section 2.1.1.3, address 138).
In address 160 L-sections FL you can set the number of line sections. If you set the number to 2
Sections or 3 Sections, a number of additional tabs for setup will appear in DIGSI. The default setting here
is 1 Section which means that the line parameters (addresses 1116, 1117, 1120 and 1121 are relevant
(see also Section 2.1.4).
If the fault location calculation is to be started by the trip command of the protection, set address 3802 START
= TRIP. In this case a fault location is only output if the device has also issued a trip. The fault location calcu-
lation can, however, also be started with each fault detection of the device (address 3802 START = Pickup).
In this case the fault location is also calculated if, for example, a different protection device cleared the fault. If
the fault is located outside the protected line, only the single-ended method is used for fault location.
To calculate the distance to fault in kilometers or miles, the device needs the reactance per unit length in Ω/km
or Ω/mile, and in the case of double-ended fault location the capacitance per unit length in μF/km or μF/mile.
For correct indication of the fault location in % of line length, the correct line length has also to be entered. For
the double-ended fault locator this information is mandatory. These setting parameters were already applied
with the Power System Data 2 (Section 2.1.4.1 at „General Line Data“).
A prerequisite for the correct indication of the fault location is furthermore that the other parameters that influ-
ence the calculation of the distance to fault have also been set correctly.
If only one
line section (address 160 = ) is set, these parameters are:
• 1116 RE/RL(Z1),
• 1117 XE/XL(Z1) or
• 1120 K0 (Z1),
• 1121 Angle K0(Z1).
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