Siemens SIPROTEC 7SJ62 Manual page 107

The rotated reference voltage defines the forward and reverse area, see Figure 2-28. The forward area is a
range of ±86° around the rotated reference voltage V
device detects forward direction. In the mirrored area, the device detects reverse direction. In the intermediate
area, the direction result is undefined.
Figure 2-28
Direction Determination of Directional Ground Element with Ground Values
Figure 2-29 shows the treatment of the reference voltage for the directional ground element, also based on a
single-pole ground fault in Phase A. Contrary to the directional phase elements, which work with the unfaulted
voltage as reference voltage, the fault voltage itself is the reference voltage for the directional ground element.
Depending on the connection of the voltage transformer, this is the voltage 3V
V . The fault current -3I
N
fault angle ϕ
. The reference voltage is rotated through the setting value 1619 ROTATION ANGLE. In this case,
sc
a rotation of -45°.
Figure 2-29
The forward area is also a range of ±86° around the rotated reference voltage V
current -3I (or I
0
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
Forward characteristic of the directional function, directional phase element
is phase offset by 180° to the fault current I
0
Rotation of the reference voltage, directional ground element with zero sequence values
) is in this area, the device detects forward direction.
N
2.3 Directional Overcurrent Protection 67, 67N
If the vector of the fault current is in this area, the
ref,rot
(as shown in Figure 2-29) or
0
and follows the fault voltage 3V
scA
ref, rot
Functions
by
0
. If the vector of the fault
107