R
X
Distance measuring zone
Phase selection
”Quadrilateral” zone
(ohm/phase)
(ohm/phase)
en05000674.vsd
IEC05000674 V1 EN-US
Figure 165: Operation 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
166. 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 "shrinks" by 2/√3, from the full RLdFw/RLdRv reach, which is valid
at load or three-phase fault.
Section 8 1MRK 504 163-UUS A
Impedance protection
350 Transformer protection RET670 2.2 ANSI
Application manual
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