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Output of the Fault Locator
The fault locator issues the following results:
• The short-circuit loop which was used to determine the fault reactance,
• Fault reactance X in Ω primary and Ω secondary,
• Fault resistance R in Ω primary and Ω secondary,
• The distance to fault d in kilometers or miles of the line proportional to the reactance, converted on the basis
of the set line reactance per unit line length,
• The distance to fault d in % of the line length, calculated on the basis of the set reactance per unit length
and the set line length.
The additional indications always show the results of single-ended fault locating.
The fault location indicated in per cent can, at the same time, be output as BCD-code (Binary Coded Decimal).
This, however, must have been preset in address 138 during the configuration of the protection functions (Sec-
tion 2.1.1.3). A further prerequisite is that the required number of binary outputs is allocated for this purpose.
10 output relays are needed. They are classified as follows:
• 4 outputs for the units (1·2
• 4 outputs for the tens (10·2
• 1 output for the hundreds (100·2
• 1 output for the ready-state annunciation „BCD dist. VALID" (No. 1152).
Once a fault was located, the corresponding binary outputs pick up. Then the output „BCD dist. VALID"
signals that the data are now valid. The duration can be set. In the event of a new fault, the data of the former
fault are cleared automatically.
The output range extends from 0 % to 195 %. Output „197" means that a negative fault was detected. Output
„199" describes an overflow, i. e. the calculated value is higher than the maximum possible value of 195 %.
Note
If no different line sections are parameterised, the distance output in kilometers, miles or percent is only accu-
rate for homogeneous lines. If the line is composed of line sections with different reactances per section, e.g.
overhead line–cable sections, the reactance calculated by the fault locating can be evaluated for the separate
calculation of the fault distance or several line sections can be set.
Line sections
The line type is determined by the line section settings. If, for instance, the line includes a cable and an over-
head line, two different sections must be configured. The system can distinguish between up to three different
line types. When configuring these line data, please note that DIGSI will only show you two or three different
tabs for setting those parameters if you have first configured that number of line sections.
Line symmetry (only for double-ended fault locating)
The asymmetry of a line can be taken into account in order to achieve higher accuracy of the double-ended
fault locating. The asymmetry is estimated on the basis of the phase arrangement. You must set the central
phase. If you do not wish an estimation of the asymmetry, it can be switched off. The system assumes lines
having a high degree of symmetry with respect to the central phase, in particular a single-level arrangement.
Figure 2-181 shows possible phase arrangements.
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
0
1
2
3
+ 1·2
+ 1·2
+ 1·2
),
0
1
2
3
+ 10·2
+ 10·2
+ 10·2
),
0
),
Functions
2.21 Fault Locator
389
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