ABB RELION REX640 Technical Manual page 1007

1MRS759142 F
DISABLE
BLOCK
Figure 559: Functional module diagram
Impedance calculation
This module calculates the positive-sequence impedance (Z1) using positive-
sequence voltage and current. For the module to calculate impedance it is required
that the positive-sequence current is above
negative-sequence current is below the
The calculated positive-sequence impedance amplitude Z1_AMPL and angle
Z1_ANGLE are available in ohms and degrees, respectively, in the Monitored data
view.
Out of step detection
The operating characteristic is a circular offset mho on the impedance plane with
two pair of blinders. The mho characteristic is defined with the
Reverse reach , and Impedance angle settings. Forward reach defines the impedance
from the origin to the edge of circle on the top side.
impedance from the origin to the edge of the circle on the bottom side. The
diameter of the mho characteristics is the sum of
settings. Two sets of blinders are defined by
intercepting at R-axis. The blinders are at the same angle as the
The second blinder of each outer and inner pair is automatically made symmetrical
with the origin of the R-X plane.
The circular mho characteristic can be further divided into two zones by setting
Zone 2 enable to "Yes". The boundary between zones is set using the setting Zone 1
reach . The lower portion of the circle, Zone 1, is separated from the upper portion,
Zone 2, by a line, perpendicular to the blinders, located at a set percentage of the
Forward reach setting from the origin.
REX640
Technical Manual
I
1
I3P
I
2
U
1
U3P
The calculated impedance is converted to ohms as the operating
characteristics are defined with the ohm settings.
For a correct operation, it is required that the setting for
is less than the setting for
Impedance
Out of step
calculation detection
Blocking
logic
Min Ps Seq current setting and the
Max Ng Seq current setting.
Forward reach and Reverse reach
Inner blinder R and Outer blinder R
Outer blinder R .
Protection functions
OPERATE
SWING
OSB
OSB_Z2
SWING_OP
Forward reach ,
Reverse reach defines the
Impedance angle .
Inner blinder R
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