ABB RELION REX640 Technical Manual page 979

1MRS759142 F
the offset mho characteristic. This is done by selecting
Impedance Chr PP Zn as "Offset Dir line".
Imp zone shape
Quadrilateral
Mho (circular)
Mho Dir line
Offset Dir line
Bullet (combi)
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 (
The directionality of the "Bullet (combi)" characteristic is defined by the directional
lines when
(combi)" characteristic, the quadrilateral resistance does not reach negative
(positive) values for "Forward" ("Reverse") direction (see
REX640
Technical Manual
Non-directional
X
X
X
X
X
Pol quantity zone = "Cross pol", "Pos. seq. volt.", "Self pol").
Directional mode Znx is "Forward" or "Reverse". For directional "Bullet
Directional mode Znx
Forward
X
R R
Pol.
X
R R
Pol.
X
R
R
X
R
R
Pol.
X
R R
Pol. = polarization method affects (mho)zone shape
Protection functions
Impedance Chr Gnd Zn and
Reverse
X
R
Pol.
X
R
Pol.
X
R
X
R
Pol.
X
R
Figure 555
).
979