the offset mho characteristic. This is done by selecting
Impedance Chr Gnd Zn
and
Impedance Chr PP Zn
as "Offset Dir line".
Non-directional Forward Reverse
Quadrilateral
Mho (circular)
Mho Dir line
Offset Dir line
Bullet (combi)
Pol. = polarization method affects (mho)zone shape
Imp zone shape
Pol. Pol.
Directional mode Znx
Pol. Pol.
Pol. Pol.
X
R
X X
X X
X X
X X
X X
R R
R R
R R
R R
R R
X
R
X
R
X
R
X
R
Figure 554: Possible combinations of Directional mode Znx and zone characteristics
settings. Pol. in the figure means that the shape of the characteristic is affected by
the selected polarization method of the mho circle, Pol quantity zone = "Cross pol",
"Pos. seq. volt.", "Self pol").
Bullet combi characteristic
If the impedance zone shape equals "Bullet (combi)", the distance protection has
a tripping characteristic which is a combination of the quadrilateral and mho. All
settings relevant to the quadrilateral and mho are applicable. The shape of the
"Bullet (combi)" characteristic is affected by the selected polarization method of the
mho circle (
Pol quantity zone
= "Cross pol", "Pos. seq. volt.", "Self pol").
The directionality of the "Bullet (combi)" characteristic is defined by the directional
lines when
Directional mode Znx
is "Forward" or "Reverse". For directional "Bullet
(combi)" characteristic, the quadrilateral resistance does not reach negative
(positive) values for “Forward” (“Reverse”) direction (see
Figure 555
).
1MRS759142 F
Protection functions
REX640
Technical Manual
979
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