ABB Relion 650 Series Technical Manual page 100

Section 5
Impedance protection
Figure 47
phase-to-phase characteristic is subject to enlargement and rotation the operate area is
transformed according to figure 48. Due to the 30-degree rotation, the angle of the blinder in
quadrant one is now 90 degrees instead of the original 60 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.
Phase selection
"Quadrilateral" zone
IEC09000049 V1 EN-US
Figure 48: Operating characteristic for FDPSPDIS (21) in forward direction for three-phase
The result from rotation of the load characteristic at a fault between two phases is presented in
fig 49. Since the load characteristic is based on the same measurement as the quadrilateral
characteristic, it will rotate with the quadrilateral characteristic clockwise by 30 degrees when
subject to a pure phase-to-phase fault. At the same time the characteristic will "shrink" by 2/√3,
from the full
94
is valid for phase-to-ground. During a three-phase fault, or load, when the quadrilateral
X
fault, ohm/phase domain
RLdFw and RLdRv reach, which is valid at load or three-phase fault.
© Copyright 2011 ABB Power Grids. All rights reserved
W
( / phase )
Distance measuring zone
W
(
R
IEC09000049-1-en.vsd
/ phase )
Line distance protection REL650
1MRK 506 326-UUS B
Technical manual