Figure 219: Overadmittance characteristic. Left figure: classical origin-centered
admittance circle. Right figure: admittance circle is set off from the origin.
Non-directional overconductance characteristic
The non-directional overconductance criterion is enabled with the
Operation mode
setting set to "Go" and
Directional mode to "Non-directional". The characteristic is
defined with two overconductance boundary lines with the
Conductance forward
and
Conductance reverse settings. For the sake of application flexibility, the
boundary lines can be tilted by 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.
In case of non-directional conductance criterion, the
Conductance reverse setting
must be set to a smaller value than
Conductance forward.
Operation is achieved when the measured admittance moves over either of the
boundary lines.
The non-directional overconductance criterion is applicable in high-
resistance earthed and compensated networks. It must not be applied
in unearthed networks.
Figure 220: 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.
1MRS757644 H
Protection functions
620 series
Technical Manual
443
