Siemens 7SC80 Manual page 250

Functions
2.13 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
for determining the direction, the displacement voltage V
part influencing the direction (active or reactive component).
The following figure illustrates an example using a complex vector diagram in which the displacement voltage
V is the reference magnitude of the real axis. The active part 3Ι0
0
to the displacement voltage V
fore suitable for ground fault direction in resonant grounded systems where quantity 3Ι0 · cos φ is relevant.
The directional limit lines are perpendicular to axis 3Ι0
[richtungskennlinie-bei-cos-messung-260602-kn, 1, en_US]
Figure 2-82
The symmetry axis can be rotated by a correction angle (parameter PHI CORRECTION) up to ± 45°. It is there-
fore possible in grounded systems, for example, to increase the sensitivity in the resistive-inductive range with
a rotation of -45°, or in case of electric machines in busbar connection in the resistive-capacitive range with a
rotation of +45° (see the following Figure). Furthermore, the symmetry axis can be rotated by 90° to deter-
mine ground faults and their direction in grounded systems.
250
and compared with setting value RELEASE DIRECT.. The example is there-
0
Directional characteristic for cos–φ–measurement
must be exceeded as well as a configurable current
0
of current 3Ι0 is calculated with reference
real
.
real
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017