ABB RELION REX640 Technical Manual page 475

1MRS759142 C
REX640
Technical Manual
GUID-903614B9-E5DF-43E9-987D-028ADAD6E9CA V1 EN
Figure 253: Non-directional overconductance characteristic. Left figure: classical
non-directional overconductance criterion. Middle figure:
characteristic is tilted with negative tilt angle. Right figure:
characteristic is tilted with positive tilt angle.
Forward directional overconductance characteristic
The forward directional overconductance criterion is enabled with the Operation
mode setting set to "Go" and Directional mode set to "Forward". The characteristic is
defined by one overconductance boundary line with the Conductance forward setting.
For the sake of application flexibility, the boundary line can be tilted with the angle
defined with the Conductance tilt Ang setting. By default, the tilt angle is zero degrees,
that is, the boundary line is a vertical line in the admittance plane. A positive tilt value
rotates the boundary line counterclockwise from the vertical axis.
Operation is achieved when the measured admittance moves over the boundary line.
The forward directional overconductance criterion is applicable in
high-resistance earthed and compensated networks. It must not be
applied in unearthed networks.
GUID-3BE28ACC-B130-4F52-B86D-BE11E5233003 V1 EN
Figure 254: Forward directional overconductance characteristic. Left figure:
classical forward directional overconductance criterion. Middle
figure: characteristic is tilted with negative tilt angle. Right figure:
characteristic is tilted with positive tilt angle.
Section 4
Protection functions
469