IEC08000437 V1 EN-US
Figure 166: Rotation of load characteristic for a fault between two phases
This rotation may seem a bit awkward, but there is a gain in selectivity by using the
same measurement as for the quadrilateral characteristic since not all phase-to-phase
loops will be fully affected by a fault between two phases. It should also provide better
fault resistive coverage in quadrant 1. The relative loss of fault resistive coverage in
quadrant 4 should not be a problem even for applications on series compensated lines.
8.10.3 Load encroachment characteristics
GUID-DD9A62C3-A56D-411B-8303-6F7BC4C6092D v1
The phase selector must at least cover the overreaching zone 2 in order to achieve
correct phase selection for utilizing single-phase autoreclosing for faults on the entire
line. It is not necessary to cover all distance protection zones. A safety margin of at
least 10% is recommended. In order to get operation from distance zones, the phase
selection output PHSELZ or PHSELI must be connected to input PHSEL on distance
zones.
1MRK 504 163-UUS A Section 8
Impedance protection
Transformer protection RET670 2.2 ANSI 351
Application manual
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