Siemens siprotec 7SA522, User Manual

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Functions
6-197
7SA522 Manual
C53000-G1176-C119-2
Figure 6-96 Fault currents and voltages on double–end fed lines
6.14.2 Applying the Function Parameter Setting
The fault location function is only in service if it was selected to
(QDEOHG
during the
configuration of the device functions (Section 5.1, address ).
If the fault location calculation is to be started by the trip command of the protection,
address
67$57
=
75,3
is set. In this case a fault location is only output if the
device has also issued a trip. The fault location calculation can however also be start-
ed with each fault detection of the device (address
67$57
=
3,&.83
). In this
case the fault location is also calculated if for example a different protection device
cleared the fault. For a fault outside the protected line, the fault location information is
not always correct, as the measured values can be distorted by e.g. intermediate in-
feeds.
To calculate the distance to fault in kilometres or miles, the device requires the reac-
tance per unit length data in
Ω
/km or
Ω
/mile. For correct indication of the fault location
in % of line length, the correct line length should also be entered. These setting pa-
rameters were already applied with the plant data (Section 6.1.3 under “General Line
Data”).
A prerequisite for the correct indication of the fault location furthermore is that the other
parameters that influence the calculation of the distance to fault have also been set
correctly. These are the addresses (refer also to Sub-section 6.1.3)
5(5/=
,
;(;/=
or
.=
,
3+,.=
.
If the parallel line compensation is used, the address must be set to
3DUDO/LQH&RPS
=
<HV
; the presetting is
1R
. Further prerequisites are that
E
1
Z
S1
Z
F1
Z
F2
Z
S2
E
2
M
R
F
I
F1
+I
F2
I
F1
I
F2
U
F1
Z
S1E
Z
F1E
Z
F2E
Z
S2E
Legend:
M Measuring location Z
S1
, Z
S2
Source impedances
E
1
, E
2
Source voltages (EMF) Z
S1E
, Z
S2E
Earth source impedances
U
F1
Fault voltage at the measuring location Z
F1
, Z
F2
Fault impedances
I
F1
, I
F2
Part fault currents Z
F1E
, Z
F2E
Earth fault impedances
I
F1
+ I
F2
Total fault current R
F
Common fault resistance
~
~
~
~
~
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