In some applications, for instance cable lines, the angle of the loop might be less than 60°. In
these applications, the settings of fault resistance coverage in forward and reverse direction,
RFFwPE and RFRvPE for phase-to-earth faults and RFFwPP and RFRvPP for phase-to-phase
faults have to be increased to avoid that FDPSPDIS characteristic shall cut off some part of the
zone characteristic. The necessary increased setting of the fault resistance coverage can be
derived from trigonometric evaluation of the basic characteristic for respectively fault type.
Phase-to-earth fault in forward direction
M13142-6 v7
With reference to figure
, the following equations for the setting calculations can be
obtained.
Index PHS in images and equations reference settings for Phase selection with
load encroachment function FDPSPDIS and index Zm reference settings for
Distance protection function (ZMQPDIS).
Section 7
1MRK 505 343-UEN B
Impedance protection
296
Application manual
Содержание Relion 670 series
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