to enlarge the resistive setting of both the Phase selection with load encroachment
and the measuring zones without interfering with the load.
A current-based phase selection is also included. The measuring elements
continuously measure three phase currents and the residual current and, compare
them with the set values.
The extensive output signals from FDPSPDIS give also important information
about faulty phase(s), which can be used for fault analysis.
8.11.3 Setting guidelines
IP14959-1 v2
The following setting guideline consider normal overhead lines applications where
φloop and φline is greater than 60°.
8.11.3.1 Load encroachment characteristics
M13142-3 v6
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 outputs STCNDZ or STCNDLE must be connected to
input on ZMQPDIS, distance measuring block.
For normal overhead lines, the angle for the loop impedance φ for phase-to-earth
fault is defined according to equation 278.
EQUATION2115 V1 EN-US (Equation 278)
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
166, 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 8 1MRK 506 369-UEN B
Impedance protection
326 Line distance protection REL670 2.2 IEC
Application manual
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