ABB Relion 670 Series Technical Reference Manual page 235

1MRK505222-UUS C
Technical reference manual
Phase selection
"Quadrilateral" zone
IEC09000049 V1 EN
Figure 108: Operating characteristic for FDPSPDIS (21) in forward direction for
three-phase fault, ohm/phase domain
The result from rotation of the load characteristic at a fault between two phases is
presented in fig 109. 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 RLdFw and RLdRv reach, which
is valid at load or three-phase fault.
Impedance protection
W
( / phase )
X
Distance measuring zone
(
R
IEC09000049-1-en.vsd
Section 6
W
/ phase )
229