(Equation 262)
(Equation 263)
The phase-to-phase measuring elements are based on the formula:
(Equation 264)
(Equation 265)
(Equation 266)
The faulted phase identification is done by comparing the measured impedance to
the operating characteristics in the impedance domain. If a measured fault loop
impedance is inside the characteristics, the corresponding phases are identified as
faulty.
The shape of the characteristic is selected with the
Z Chr Mod Ph Sel GFC
setting.
Two shapes are available.
• "Mho (circular)", Non-directional mho
• "Quadrilateral", Non-directional quadrilateral
The two shapes can be flexibly configured. It is possible to set the reactive reaches
independently in forward and in reverse direction and for phase-to-earth (Gnd) and
phase-to-phase (PP) measurement elements, for example, the
X Gnd Fwd reach GFC
,
X Gnd Rv reach GFC
,
X PP Fwd reach GFC
and
X PP Rv reach GFC
settings. Also,
the resistive reach in case of quadrilateral characteristic can be set both forward
and reverse independently of reactive reaches, for example, the
Ris Gnd Fwd Rch
GFC, Ris Gnd Rv Rch GFC, Ris PP Fwd Rch GFC
and
Ris PP Rv Rch GFC
settings. The
characteristic is always mirror-symmetric around the reactance axis.
The impedance settings are in primary ohms.
In case of heavy loaded feeders, the optional load encroachment logic can be
enabled with the
Load Dsr mode GFC
setting. The logic reserves an area for load
Protection functions
1MRS759142 F
954 REX640
Technical Manual
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