Siemens 7SR51 - Page 122

Parameter: Fault Locator > Secy Z+ Per Unit Distance
•
Default Setting: 0.5 Ω
The system positive sequence impedance per unit – see Display Units.
Parameter: Fault Locator > Display Units
•
Default Setting: Percent
The distance top fault is presented as a percentage of line length or a distance in miles or kilometers.
Parameter: Fault Locator > System Earthing
•
Default Setting: Normal
When the power system is earthed through compensation (Peterson) coils, the earth fault currents are
extremely low and are not proportional to fault location. Impedance based fault location cannot be used
for earth faults. Phase to phase fault location can be estimated. On networks of this type it is possible to
have 2 earth faults on the network simultaneously on different phases of the same circuit which will
appear as a phase to phase fault (Cross Country fault). In these cases the measured impedance cannot
give an accurate estimate of the fault condition. The device provides detection of this condition using the
measured zero sequence voltage to positive sequence voltage ratio (U
0
/U
1
) to allow the possible cross
country fault to be reported.
Parameter: Fault Locator > U
0
/U
1
Ratio
•
Default Setting: 0.1
The system zero sequence voltage to positive sequence voltage ratio.
Configuration > Data Storage > Fault Locator
Parameter Range Default Setting
21FL Fault locator Enabled
Disabled
Line angle 0 to 90°, Δ 1° 75°
EF comp Z
0
/Z
1
ratio 0 to 10, Δ 0.01 2.5
EF comp Z
0
angle 0 to 359°, Δ 1° 75°
Z+ Impedance 0 to 100 Ω, Δ 0.1 Ω
101 to 250 Ω, Δ 1 Ω
10 Ω
Secy Z+ per unit distance 0.0005 to 5Ω, Δ 0.0005 Ω 0.5 Ω
Display units Percent, Kilometers, Miles Percent
System earthing Normal, Compensated Normal
V
0
/V
1
Ratio 0 to 1, Δ 0.01
IEC 61850 Functional Information Mapping
RFLO.Mod
Information
Element Disabled 1 0 0
Element Inhibited x 1 0
RFLO.Mod.stVal 5 2 1
Device Functionality
3.6 Data Storage
122 Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019