ABB RED615 Technical Manual page 335

1YHT530004D05 D
615 series
Technical Manual
For the sake of application flexibility, the boundary lines can be tilted by the angle
defined with the Conductance tilt Ang and Susceptance tilt Ang settings. By
default, the tilt angles are zero degrees, that is, the boundary lines are straight lines
in the admittance plane. A positive Conductance tilt Ang value rotates the
overconductance boundary line counterclockwise from the vertical axis. A positive
Susceptance tilt Ang value rotates the oversusceptance boundary line
counterclockwise from the horizontal axis.
In case of the non-directional conductance and susceptance criteria, the
Conductance reverse setting must be set to a smaller value than Conductance
forward and the Susceptance reverse setting must be set to a smaller value than
Susceptance forward.
Operation is achieved when the measured admittance moves outside the
characteristic.
The combined overconductance and oversusceptance criterion is applicable in high-
resistance earthed, unearthed and compensated networks or in the systems where
the system earthing may temporarily change during normal operation from
compensated to unearthed system.
Im(Yo)
OPERATE
Susceptance forward
Conductance forward
GUID-1A21391B-A053-432B-8A44-7D2BF714C52D V1 EN
Figure 167: Combined forward directional overconductance and forward
directional oversusceptance characteristic. Left figure: the
Conductance tilt Ang and Susceptance tilt Ang settings equal zero
degrees. Right figure: the setting Conductance tilt Ang > 0 degrees
and the setting Susceptance tilt Ang < 0 degrees.
OPERATE
OPERATE
Susceptance forward
Re(Yo)
Conductance forward
OPERATE
Section 4
Protection functions
Im(Yo)
Conductance tilt Ang >0
OPERATE
Susceptance tilt Ang <0
Re(Yo)
OPERATE
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