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current. Consequently, the result of direction determination is as reliable as possible.
the relationship based on a 1-phase ground fault in phase A. The short-circuit current I
voltage by the short-circuit angle φ
rotated positively (counterclockwise) by the setting value of the Rotation angle of ref. volt. param-
eter. In the scenario illustrated here, the rotation is +45
[dwdocp33-070611-01.tif, 2, en_US]
Figure 6-56
The rotated reference voltage defines the forward and reverse range, as shown in
range is calculated as ±88
located in this range, the device decides on the forward direction. In the mirrored range, the device decides on
the backward direction. In the intermediate range, the direction is undetermined.
[dwdocp34-240611-01.tif, 2, en_US]
Figure 6-57
Direction Determination for Test Purposes
If you activate the binary input signal >Test of direction, the direction is determined and indicated even
without the current threshold being exceeded in one of the stages. The direction can be determined as soon
as current and voltage are greater than approx. 7 % of their secondary rated values.
SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
. The reference voltage, in this case V
sc
Rotation of the Reference Voltage, Phase-Measuring Element
o
around the rotated reference voltage V
Forward Characteristic of the Directional Function, Phase-Measuring Element
Protection and Automation Functions
6.6 Directional Overcurrent Protection, Phases
for measuring element A, is
BC
o
.
Figure
. If the short-circuit current vector is
ref,rot
Figure 6-56
illustrates
lags the short-circuit
scA
6-57. The forward
435
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