R
X
Distance measuring zone
Directional line
Load encroachment
characteristic
"Phase selection"
"quadrilateral" zone
en05000673.vsd
IEC05000673 V1 EN-US
Figure 139: Operating characteristic in forward direction when load encroachment is
activated
Figure
is valid for phase-to-ground. During a three-phase fault, or load, when the quadrilateral
phase-to-phase characteristic is subject to enlargement and rotation the operate area is
transformed according to figure
. Notice in particular what happens with the resistive blinders
of the "phase selection" "quadrilateral" zone. Due to the 30-degree rotation, the angle of the
blinder in quadrant one is now 100 degrees instead of the original 70 degrees (if the angle setting
is 70 degrees). The blinder that is nominally located to quadrant four will at the same time tilt
outwards and increase the resistive reach around the R-axis. Consequently, it will be more or less
necessary to use the load encroachment characteristic in order to secure a margin to the load
impedance.
1MRK 502 066-UUS B
Section 7
Impedance protection
283
Technical manual
Содержание Relion 670 series
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