R
X
Distance measuring zone
Directional line
Load encroachment
characteristic
"Phase selection"
"quadrilateral" zone
en05000673.vsd
IEC05000673 V1 EN-US
Figure 164:
Operation characteristic in forward direction when load encroachment
is enabled
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. 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 504 163-UUS A
Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI
349
Application manual
Содержание RELION RET670
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