R
X
Distance measuring zone
Phase selection
”Quadrilateral” zone
IEC09000049-1-en.vsd
)/(
phaseW
)/( phaseW
IEC09000049 V1 EN
Figure 176: Operating characteristic for FRPSPDIS (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.
1MRK505222-UUS C Section 6
Impedance protection
337
Technical reference manual
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